As filed with the Securities and Exchange Commission on August 12, 2003
                      Registration Statement No. 333-106797

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
                            ------------------------
                               AMENDMENT NO. 1 TO
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                               CYTOGEN CORPORATION
            --------------------------------------------------------
             (Exact Name of Registrant as Specified in Its Charter)

            Delaware                                            22-2322400
---------------------------------                        -----------------------
  (State or Other Jurisdiction                               (I.R.S. Employer
of Incorporation or Organization)                         Identification Number)

                        650 College Road East, 3rd Floor
                           Princeton, New Jersey 08540
                                 (609) 750-8200
       ------------------------------------------------------------------
          (Address, Including Zip Code, and Telephone Number, Including
             Area Code, of Registrant's Principal Executive Offices)
                            Donald L. Novajosky, Esq.
                                 Director, Legal
                               Cytogen Corporation
                        650 College Road East, 3rd Floor
                           Princeton, New Jersey 08540
                                 (609) 750-8222
        ----------------------------------------------------------------
            (Name, Address, Including Zip Code, and Telephone Number,
                   Including Area Code, of Agent for Service)

                       -----------------------------------
                                    COPY TO:
                           Richard S. Mattessich, Esq.
                                Hale and Dorr LLP
                        650 College Road East, 4th Floor
                           Princeton, New Jersey 08540
                                 (609) 750-7600
                       -----------------------------------

  Approximate  date of  commencement  of  proposed  sale to  public:  As soon as
  practicable after this Registration Statement becomes effective.

      If the only  securities  being  registered  on this Form are being offered
  pursuant  to  dividend  or  interest  reinvestment  plans,  please  check  the
  following box. [ ]

      If any of the securities  being  registered on this Form are to be offered
  on a delayed or continuous basis pursuant to Rule 415 under the Securities Act
  of 1933,  other than  securities  offered only in connection  with dividend or
  interest reinvestment plans, check the following box. [X]

      If this Form is filed to register  additional  securities  for an offering
  pursuant to Rule 462(b) under the Securities  Act,  please check the following
  box and list the Securities Act  registration  statement number of the earlier
  effective registration statement for the same offering. _______.

      If this Form is a  post-effective  amendment filed pursuant to Rule 462(c)
  under the Securities  Act, check the following box and list the Securities Act
  registration  statement number of the earlier effective registration statement
  for the same offering. __________.

      If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [ ]

                      -----------------------------------





                                    CALCULATION OF REGISTRATION FEE
----------------------------------------------------------------------------------------------------
                                                        Proposed        Proposed
                                                         Maximum         Maximum
                                          Amount        Aggregate       Aggregate      Amount Of
                                          To Be           Price          Offering    Registration
   Title Of Shares To Be Registered     Registered     Per Unit(1)       Price(1)       Fee(2)
----------------------------------------------------------------------------------------------------

                                                                            
Common stock,
   $.01 par value per share...........  1,368,422         $7.43        $10,167,375      $822.54
----------------------------------------------------------------------------------------------------


(1)      Estimated  solely for  purposes of  calculating  the  registration  fee
         pursuant to Rule 457(c) under the  Securities  Act of 1933, as amended,
         and based  upon the  average  of the high and low  prices on the Nasdaq
         National Market on June 26, 2003.


(2)      The Company has  previously  paid such filing fee to the  Commission on
         July 3, 2003.

                      -----------------------------------

THE COMPANY HEREBY AMENDS THIS  REGISTRATION  STATEMENT ON SUCH DATE OR DATES AS
MAY BE  NECESSARY  TO DELAY ITS  EFFECTIVE  DATE UNTIL THE COMPANY  SHALL FILE A
FURTHER AMENDMENT WHICH  SPECIFICALLY  STATES THAT THIS  REGISTRATION  STATEMENT
SHALL  THEREAFTER  BECOME  EFFECTIVE  IN  ACCORDANCE  WITH  SECTION  8(A) OF THE
SECURITIES  ACT OF  1933  OR  UNTIL  THE  REGISTRATION  STATEMENT  SHALL  BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION,  ACTING PURSUANT TO SAID SECTION 8(A),
SHALL DETERMINE.








THE  INFORMATION  IN THIS  PROSPECTUS  IS NOT COMPLETE  AND MAY BE CHANGED.  THE
SELLING  STOCKHOLDERS  NAMED IN THIS  PROSPECTUS  MAY NOT SELL THESE  SECURITIES
UNTIL  THE  REGISTRATION  STATEMENT  FILED  WITH  THE  SECURITIES  AND  EXCHANGE
COMMISSION  IS  EFFECTIVE.  THIS  PROSPECTUS  IS  NOT AN  OFFER  TO  SELL  THESE
SECURITIES AND THE SELLING  STOCKHOLDERS ARE NOT SOLICITING  OFFERS TO BUY THESE
SECURITIES IN ANY JURISDICTION WHERE THE OFFER OR SALE IS NOT PERMITTED.

                  SUBJECT TO COMPLETION, DATED AUGUST 12, 2003

PROSPECTUS

                               CYTOGEN CORPORATION

                        1,368,422 SHARES OF COMMON STOCK


         This prospectus  relates to resales of shares of up to 1,368,422 shares
of our common stock,  $0.01 par value per share,  all of which are being sold by
certain  institutional  investors set forth in this prospectus under the section
titled  "Selling  Stockholders"  on page 19. We are not selling any shares under
this prospectus.  Accordingly, we will not receive any proceeds from the sale of
shares hereunder.

         Our common  stock is traded on the  Nasdaq  National  Market  under the
symbol  "CYTO." On June 25, 2003,  the closing sale price of our common stock on
Nasdaq was $7.09 per share.  You are urged to obtain current  market  quotations
for our common stock.


                      ------------------------------------

         INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. SEE "RISK
FACTORS" COMMENCING ON PAGE 4.

                      ------------------------------------


         NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS
PROSPECTUS  IS TRUTHFUL OR  COMPLETE.  ANY  REPRESENTATION  TO THE CONTRARY IS A
CRIMINAL OFFENSE.

                The date of this prospectus is August [ ], 2003.








                                         TABLE OF CONTENTS

----------------------------------------------------------------------------------------------------
                                                                                                
Prospectus Summary...............................................................................  2

Cytogen Corporation..............................................................................  2

The Offering.....................................................................................  3

Reverse Stock Split..............................................................................  3

Risk Factors.....................................................................................  4
      We have a history of operating losses and an accumulated deficit and expect to
        incur losses in the future...............................................................  4

      We depend on sales of ProstaScint and Quadramet for the majority of our near-
        term revenues............................................................................  5

      We depend on acceptance of our products by the medical community for the
        continuation of our revenue..............................................................  5

      The reduced workforce at AxCell may not be able to implement AxCell's business
        plan.....................................................................................  5

      We may need to raise additional capital, which may not be available........................  6

      Our capital raising efforts may dilute stockholder interests...............................  6

      We may need to raise funds other than through the issuance of equity securities............  7

      Our products, generally, are in the early stages of development and
        commercialization and we may never achieve the revenue goals set forth in our
        business plan............................................................................  7

      Our PSMA product development program is novel and, consequently,
        inherently risky.........................................................................  7

      All of our potential oncology products will be subject to the risks of failure
        inherent in the development of diagnostic or therapeutic products based on new
        technologies.............................................................................  8

      Competition in our field is intense and likely to increase.................................  9

      We rely heavily on our collaborative partners.............................................. 10

      Our business could be harmed if certain agreements expire or are terminated early.......... 10

      We have limited sales, marketing and distribution capabilities for our products............ 11

      There are risks associated with the manufacture and supply of our products................. 11

      Failure of consumers to obtain adequate reimbursement from third-party payors
        could limit market acceptance and affect pricing of our products......................... 12

      If we are unable to comply with applicable governmental regulation we may not
        be able to continue our operations....................................................... 12

      We could be negatively impacted by future interpretation or implementation of
        federal and state fraud and abuse laws, including anti-kickback laws, the Federal
        Stark Law and other federal and state anti-referral laws................................. 14

      We depend on attracting and retaining key personnel........................................ 14

      Our business exposes us to potential liability claims that may exceed our financial
        resources, including our insurance coverage, and may lead to the curtailment or
        termination of our operations............................................................ 15

      Our business involves environmental risks that may result in liability..................... 15

      Our intellectual property is difficult to protect.......................................... 16

----------------------------------------------------------------------------------------------------

                                                -i-






----------------------------------------------------------------------------------------------------
      Our security measures may not protect our unpatented proprietary technology................ 17

      We are currently subject to patent litigation.............................................. 17

      Our stock price has been and may continue to be volatile, and your investment in
        our stock could decline in value or fluctuate significantly.............................. 18

      We have adopted various anti-takeover provisions which may affect the market
        price of our common stock and prevent or frustrate attempts by our stockholders
        to replace or remove our management team................................................. 19

      The liquidity of our common stock could be adversely affected if we are delisted
        from The Nasdaq National Market.......................................................... 19

      A large number of our shares are eligible for future sale which may adversely
        impact the market price of our common stock.............................................. 20

      Because we do not intend to pay, and have not paid, any cash dividends on our
        shares of common stock, our stockholders will not be able to receive a return on
        their shares unless the value of our shares appreciates and they sell them............... 21

Special Note Regarding Forward-Looking Statements................................................ 22

Use of Proceeds.................................................................................. 22

Selling Stockholders............................................................................. 23

Plan of Distribution............................................................................. 24

Legal Matters.................................................................................... 25

Experts.......................................................................................... 25

Where You Can Find More Information.............................................................. 26

Information Incorporated By Reference............................................................ 26

Indemnification of Officers and Directors........................................................ 27

----------------------------------------------------------------------------------------------------


                                                -ii-





                               PROSPECTUS SUMMARY

THIS SUMMARY HIGHLIGHTS  IMPORTANT FEATURES OF THIS OFFERING AND THE INFORMATION
INCLUDED OR INCORPORATED BY REFERENCE IN THIS PROSPECTUS.  THIS SUMMARY DOES NOT
CONTAIN ALL OF THE INFORMATION  THAT YOU SHOULD CONSIDER BEFORE INVESTING IN OUR
COMMON STOCK. YOU SHOULD READ THE ENTIRE  PROSPECTUS  CAREFULLY,  ESPECIALLY THE
RISKS OF INVESTING IN OUR COMMON STOCK DISCUSSED UNDER "RISK FACTORS."

                               CYTOGEN CORPORATION

         Cytogen    Corporation    is   a    product-driven,    oncology-focused
biopharmaceutical  company  with an  established  and  growing  product  line in
prostate cancer and other areas of oncology.  Our FDA-approved  products include
ProstaScint(R)  (a  monoclonal  antibody-based  imaging  agent used to image the
extent  and  spread of  prostate  cancer);  Quadramet(R)  (a  therapeutic  agent
marketed  for the relief of bone pain in prostate and other types of cancer) and
NMP22  BladderChek(TM)  (a  point-of-care,  in vitro diagnostic test for bladder
cancer).  Our pipeline is comprised of product  candidates at various  stages of
clinical  development,  including fully human  monoclonal  antibodies and cancer
vaccines based on PSMA prostate  specific membrane antigen  technology,  or PSMA
technologies, which we exclusively licensed from Memorial Sloan-Kettering Cancer
Center.  We also conduct research in cellular  signaling through our subsidiary,
AxCell Biosciences.

         In addition to the products listed above, in August,  2000, we expanded
our product pipeline by entering into marketing,  license and supply  agreements
with  Advanced  Magnetics,  Inc. for  Combidex(R),  which is an  investigational
magnetic   resonance   imaging  (MRI)   contrast   agent  that  assists  in  the
differentiation of metastatic from non-metastatic lymph nodes. We hold exclusive
United States marketing rights to Combidex. Advanced Magnetics is continuing its
discussions with the FDA relating to outstanding  issues regarding an approvable
letter  received from the FDA in June,  2000, in an effort to bring  Combidex to
market.

         We have had a history of operating losses since our inception. We had a
net loss of $2.0 million for the three months ended March 31, 2003 and had a net
loss of  $15.7  million  for the year  ended  December  31,  2002.  Although  we
continually  look to expand  our  product  pipeline,  we  currently  rely on two
products,  ProstaScint and Quadramet,  for substantially all of our revenues. In
addition, we have, from time to time, ceased sales of certain products,  such as
BrachySeed  and OncoScint  CR/OV,  that we previously  believed  would  generate
significant  revenues for our business.  Our products are subject to significant
regulatory  review  by the FDA and  other  federal  and  state  agencies,  which
requires  significant  time and  expenditures in seeking product  approvals.  In
addition,  we  rely  on  collaborative  partners  to  a  significant  degree  to
manufacture  our products,  to secure raw  materials,  and to provide  licensing
rights to their proprietary products for us to sell and market to others.

         We  are  a  Delaware  corporation.   We  were  incorporated  and  began
operations in 1980 under the name Hybridex, Inc. and changed our name to Cytogen
Corporation in April 1980. Our executive offices are located at 650 College Road
East,  Suite 3100,  Princeton,  New Jersey 08540,  our telephone number is (609)
750-8200 and our Internet address is  http://www.cytogen.com  The information on
our Internet website is not incorporated by reference in this prospectus. Unless
the context otherwise requires  references in this prospectus to "Cytogen",  the
"Company,"  "we,"  "us,"  and  "our"  refer  to  Cytogen   Corporation  and  our
subsidiaries.

         ProstaScint(R) and OncoScint(R) are registered United States trademarks
of Cytogen  Corporation.  All other trade  names,  trademarks  or service  marks
appearing in this  Registration  Statement on Form S-3 are the property of their
respective  owners,  and not the property of Cytogen  Corporation  or any of our

                                      -2-


subsidiaries. Quadramet(R) is a trademark of The Dow Chemical Company used under
license by Cytogen.

                                  THE OFFERING

Common Stock offered by selling
stockholders......................... 1,368,422 shares

Use of proceeds...................... Cytogen will not receive any proceeds from
                                      the sale of shares in this offering

Nasdaq National Market symbol........ CYTO

                               REVERSE STOCK SPLIT

         On October 25, 2002, we received  approval from our  stockholders  at a
duly called and held special  meeting of  stockholders to effect a reverse split
of our common stock.  Our Board of Directors  thereafter  approved a one-for-ten
reverse split of our outstanding,  issued and authorized shares of common stock,
which  became  effective  on October  25,  2002.  All  numbers set forth in this
Registration  Statement  on Form S-3  reflect  the  effect  of such  one-for-ten
reverse stock split.








                                      -3-



                                  RISK FACTORS

         INVESTING  IN OUR  COMMON  STOCK  INVOLVES A HIGH  DEGREE OF RISK.  YOU
SHOULD  CAREFULLY  CONSIDER THE RISKS AND  UNCERTAINTIES  DESCRIBED BELOW BEFORE
PURCHASING OUR COMMON STOCK. IF ANY OF THE FOLLOWING  RISKS ACTUALLY OCCUR,  OUR
BUSINESS,  FINANCIAL  CONDITION OR RESULTS OF OPERATIONS WOULD LIKELY SUFFER. IN
THAT CASE,  THE TRADING  PRICE OF OUR COMMON STOCK COULD FALL,  AND YOU MAY LOSE
ALL OR PART OF THE MONEY YOU PAID TO BUY OUR COMMON STOCK.

WE HAVE A HISTORY OF OPERATING  LOSSES AND AN ACCUMULATED  DEFICIT AND EXPECT TO
INCUR LOSSES IN THE FUTURE.

Given the high  level of  research  and  development  and  related  expenditures
associated with our business and our inability to generate  revenues  sufficient
to cover such expenditures,  we have had a history of operating losses since our
inception.  We had a net loss of $2.0  million for the three  months ended March
31,  2003 and had a net loss of $15.7  million for the year ended  December  31,
2002.  Beginning in December  2001,  we began to equally  share the costs of the
PSMA Development  Company LLC and we expect to incur  significant and increasing
costs in the future to fund our share of the joint venture. We had a net loss of
$12.1  million for the year ended  December 31, 2001. We had a net loss of $27.3
million for the year ended December 31, 2000 which included  non-cash charges of
$13.1 million for the acquisition of product  candidate  rights and $4.3 million
for the  cumulative  effect of an  accounting  change  following the adoption of
Securities and Exchange  Commission Staff Accounting Bulletin No. 101. We had an
accumulated deficit of $358.3 million as of March 31, 2003.

In order  to  develop  and  commercialize  our  technologies,  particularly  our
prostate specific membrane antigen, or PSMA, technology, and expand our oncology
products, we expect to incur significant increases in our expenses over the next
several  years.  As a result,  we will need to generate  significant  additional
revenue to become profitable.

To date,  we have  taken  affirmative  steps to reduce  our  trend of  operating
losses. Such steps include, among other things: (i) the effective monitoring and
management  of  expenses  relating  to  research  and  development,  selling and
marketing,  and other general and administrative  matters; (ii) undergoing steps
to  realign  and  implement  our  focus  as a  product-driven,  oncology-focused
biopharmaceutical  company;  (iii)  the  establishment  and  maintenance  of our
in-house  specialty sales force;  (iv) enhancing our marketed product  portfolio
through marketing alliances and strategic arrangements such as we have done with
the Combidex  product,  which we intend to market if this product is approved by
the FDA; (v) the  reacquisition  of North American and Latin American  marketing
rights to  Quadramet  from  Berlex  Laboratories  in August  2003;  and (vi) the
addition of NMP22 BladderChek to our marketed product portfolio.

Although  we  have  taken  these  affirmative  steps,  we may  never  be able to
successfully implement them, and our ability to generate and sustain significant
additional  revenues  or achieve  profitability  will  depend  upon the  factors
discussed  elsewhere in this "Risk Factors"  section,  as well as numerous other
factors outside of our control, including:

     -    development  of  competing  products  that are more  effective or less
          costly than ours;

     -    our  ability  to  develop  and  commercialize  our  own  products  and
          technologies; and

     -    our ability to achieve  increased sales for our existing  products and
          sales for any new products.

As a result, we may never be able to generate or sustain significant  additional
revenue or achieve profitability.

                                      -4-


WE  DEPEND  ON  SALES OF  PROSTASCINT  AND  QUADRAMET  FOR THE  MAJORITY  OF OUR
NEAR-TERM REVENUES.

We expect  ProstaScint and Quadramet to account for a significant  percentage of
our product related revenues in the near future. For the year ended December 31,
2002,  revenues from  ProstaScint  and royalties  from  Quadramet  accounted for
approximately 64% and 15%, respectively, of our product related revenues; and in
the three-months  ended March 31, 2003,  revenues from ProstaScint and royalties
from Quadramet  accounted for  approximately 69% and 19%,  respectively,  of our
product  related  revenues.  If ProstaScint or Quadramet do not achieve  broader
market acceptance, either because we fail to effectively market such products or
our competitors  introduce  competing  products,  we may not be able to generate
sufficient  revenue to become  profitable.  In 2002, our product related revenue
included revenue from BrachySeed, which accounted for 20% of our product related
revenue.  In  January  2003,  we served  notice of  termination  for each of our
License  and  Distribution   Agreement  and  Product  Manufacturing  and  Supply
Agreement  with  Draximage  with  respect  to  both  the  BrachySeed  I-125  and
BrachySeed  Pd-103  products.  As a result,  effective  January 24, 2003,  we no
longer accept or fill new orders for the BrachySeed products.  In April 2003, we
entered into an agreement  with  Draximage  formally  terminating  each of these
agreements.

Generating  market  acceptance  and sales of our  products  is  difficult,  time
consuming and uncertain.  We launched  ProstaScint in October 1996, Quadramet in
March 1997, OncoScint CR/OV in December 1992, BrachySeed I-125 in February 2001,
BrachySeed Pd-103 in May 2002 and NMP22  BladderChek in November 2002.  Revenues
for  ProstaScint  grew from $55,000 in 1996 to $7.9  million in 2002.  Royalties
from sales of Quadramet  went from $3.3 million in 1997 to $1.8 million in 2002.
Royalties  from sales of Quadramet in the initial years of sales were  supported
by a guaranteed  minimum  revenue  arrangement  with the third party licensor of
Quadramet.  OncoScint CR/OV was discontinued in December 2002 and the BrachySeed
products were  discontinued in January 2003.  NMP22  BladderChek is a relatively
new product for us.  Currently,  all of our  revenues  are derived from sales of
ProstaScint,  Quadramet  and  NMP22  BladderChek  products,  as well as  certain
license and contract revenues.

WE DEPEND  ON  ACCEPTANCE  OF OUR  PRODUCTS  BY THE  MEDICAL  COMMUNITY  FOR THE
CONTINUATION OF OUR REVENUES.

Because our marketed  products  contribute  the majority of our product  related
revenues, our business,  financial condition and results of operations depend on
their  acceptance as safe,  effective and  cost-efficient  alternatives to other
available   treatment  and  diagnostic   protocols  by  the  medical  community,
including:

     -    health care providers, such as hospitals and physicians; and

     -    third-party payors,  including Medicare,  Medicaid,  private insurance
          carriers and health maintenance organizations.

Our  customers,   including  technologists  and  physicians,  must  successfully
complete our Partners in  Excellence  Program,  or PIE  Program,  a  proprietary
training program designed to promote the correct  acquisition and interpretation
of  ProstaScint  images.  This  product is  technique  dependent  and requires a
learning commitment by technologists and physicians and their acceptance of this
product as part of their treatment practices. If ProstaScint or Quadramet do not
achieve  broader market  acceptance,  we may not be able to generate  sufficient
revenue to become profitable.

THE REDUCED  WORKFORCE AT AXCELL MAY NOT BE ABLE TO IMPLEMENT  AXCELL'S BUSINESS
PLAN.

In September 2002, we implemented the  restructuring  of our subsidiary,  AxCell
Biosciences  Corporation,  in an effort to reduce expenses and position  Cytogen


                                      -5-


for stronger long-term growth in oncology.  As a result, we reduced our staff at
AxCell by  seventy-five  percent,  suspended  certain  projects  at  AxCell  and
implemented other cost-saving measures.

The technologies under development at AxCell are complex and remain commercially
unproven.  Even if we are able to develop and  commercialize  a product  through
AxCell,  there may be fewer than 100 pharmaceutical  companies and biotechnology
companies that are potential customers for such technology or product.

Although we believe that we have  retained the AxCell  personnel  who are key to
achieving AxCell's goals and implementing its strategies, such reduced workforce
may not be able to implement AxCell's current business plan. The further loss of
any of  AxCell's  personnel  could have a material  adverse  effect on  AxCell's
ability to achieve its goals.

WE MAY NEED TO RAISE ADDITIONAL CAPITAL, WHICH MAY NOT BE AVAILABLE.

We have  incurred  negative  cash  flows from  operations  since  inception.  We
expended, and will need to continue to expend, substantial funds to complete our
planned product  development  efforts,  including our PSMA programs.  Our future
capital  requirements  and the  adequacy of our  available  funds depend on many
factors, including:

     -    successful commercialization of our products;

     -    acquisition of complementary products and technologies;

     -    magnitude, scope and results of our product development efforts;

     -    progress of preclinical studies and clinical trials;

     -    progress toward regulatory approval for our products;

     -    costs of filing,  prosecuting,  defending and enforcing  patent claims
          and other intellectual property rights;

     -    competing technological and market developments; and

     -    expansion  of  strategic   alliances  for  the  sale,   marketing  and
          distribution of our products.

We may raise additional capital through public or private equity offerings, debt
financings or additional  collaborations and licensing arrangements.  Additional
financing may not be available to us when needed,  or, if available,  we may not
be able to obtain  financing on terms  favorable to our  stockholders  or us. If
adequate  funds  are not  available,  we may not be  able  to  conduct  research
activities, preclinical studies, clinical trials or other activities relating to
the successful  commercialization  of our products on a timely basis, if at all,
with the result that our business could be significantly and adversely affected.

OUR CAPITAL RAISING EFFORTS MAY DILUTE STOCKHOLDER INTERESTS.

If we raise additional capital by issuing equity  securities,  the issuance will
result in ownership  dilution to our existing  stockholders.  The extent of such
dilution will vary based upon the amount of capital raised.


                                      -6-

WE MAY NEED TO RAISE FUNDS OTHER THAN THROUGH THE ISSUANCE OF EQUITY SECURITIES.

If we raise additional funds through collaborations and licensing  arrangements,
we may be  required  to  relinquish  rights to  certain of our  technologies  or
product  candidates or to grant licenses on unfavorable  terms. If we relinquish
rights or grant licenses on unfavorable  terms, we may not be able to develop or
market products in a manner that is profitable to us.

OUR  PRODUCTS,   GENERALLY,   ARE  IN  THE  EARLY  STAGES  OF  DEVELOPMENT   AND
COMMERCIALIZATION  AND WE MAY NEVER  ACHIEVE THE REVENUE  GOALS SET FORTH IN OUR
BUSINESS PLAN.

We began operations in 1980 and have been engaged primarily in research directed
toward the development,  commercialization  and marketing of products to improve
diagnosis  and  treatment of cancer and other  diseases.  In December  1992,  we
introduced  OncoScint CR/OV, and subsequently  ceased selling and marketing this
product in December  2002. In October 1996, we introduced for commercial use our
ProstaScint  imaging agent.  In March 1997, we introduced for commercial use our
Quadramet  therapeutic  product.  In 2001,  we  launched  the iodine  version of
BrachySeed.  In May 2002, we launched the palladium  version of  BrachySeed.  In
January 2003, we discontinued our marketing and sale of the BrachySeed products.
In November  2002, we began  promoting  NMP22  BladderChek  to urologists in the
United States.

Our PSMA  technologies  are still in the early  stages of  development.  We have
significantly reduced operations at our AxCell subsidiary,  which is responsible
for the development certain of our technologies.  We may be unable to develop or
commercialize these products and technologies.

Our business is therefore subject to the risks inherent in the development of an
early stage biopharmaceutical business enterprise, such as the need:

     -    to obtain sufficient capital to support the expenses of developing our
          technology and commercializing our products;

     -    to ensure that our products are safe and effective;

     -    to obtain regulatory approval for the use and sale of our products;

     -    to  manufacture  our  products  in  sufficient  quantities  and  at  a
          reasonable cost;

     -    to develop a sufficient market for our products; and

     -    to attract  and retain  qualified  management,  sales,  technical  and
          scientific staff.

The problems  frequently  encountered  using new technologies and operating in a
competitive  environment  also may affect our  business.  If we fail to properly
address these risks and attain our business  objectives,  our business  could be
significantly and adversely affected.

OUR PSMA  PRODUCT  DEVELOPMENT  PROGRAM IS NOVEL AND,  CONSEQUENTLY,  INHERENTLY
RISKY.

We are subject to the risks of failure  inherent in the  development  of product
candidates based on new technologies, including our PSMA technology. These risks
include the possibility that:

     -    the technologies we use will not be effective;

                                      -7-

     -    our product candidates will be unsafe;

     -    our product  candidates will fail to receive the necessary  regulatory
          approvals;

     -    the product candidates will be hard to manufacture on a large scale or
          will be uneconomical to market; and

     -    we will not successfully overcome  technological  challenges presented
          by our potential new products.

Our other research and development  programs involve  similarly novel approaches
to human  therapeutics.  Consequently,  there is no precedent for the successful
commercialization of therapeutic products based on our PSMA technologies.  If we
fail to develop such products, our business could be significantly and adversely
affected.

ALL OF OUR POTENTIAL  ONCOLOGY  PRODUCTS WILL BE SUBJECT TO THE RISKS OF FAILURE
INHERENT IN THE  DEVELOPMENT OF DIAGNOSTIC OR THERAPEUTIC  PRODUCTS BASED ON NEW
TECHNOLOGIES.

Product  development  for cancer  treatment  involves a high degree of risk. The
product  candidates  we  develop,  pursue  or offer may not prove to be safe and
effective,  may not receive the necessary regulatory approvals, may be precluded
by  proprietary  rights of third parties or may not  ultimately  achieve  market
acceptance.   These  product  candidates  will  require  substantial  additional
investment,  laboratory  development,  clinical testing and regulatory approvals
prior  to  their  commercialization.  We may  experience  difficulties,  such as
inability to receive timely  regulatory  approvals,  that could delay or prevent
the successful development, introduction and marketing of new products.

Before we obtain  regulatory  approvals  for the  commercial  sale of any of our
products under development,  we must demonstrate through preclinical studies and
clinical  trials that the product is safe and efficacious for use in each target
indication.  The results from preclinical  studies and early clinical trials may
not be predictive of results that will be obtained in large-scale  testing.  Our
clinical trials may not demonstrate  safety and efficacy of a proposed  product,
and therefore,  may not result in marketable  products. A number of companies in
the  biotechnology  industry  have  suffered  significant  setbacks  in advanced
clinical trials, even after promising results in earlier trials. Clinical trials
or marketing of any potential  diagnostic or therapeutic  products may expose us
to liability claims for the use of these diagnostic or therapeutic  products. We
may not be able to maintain product liability  insurance or sufficient  coverage
may not be available at a reasonable cost. In addition, as we develop diagnostic
or therapeutic products internally, we will have to make significant investments
in  diagnostic  or  therapeutic  product  development,   marketing,   sales  and
regulatory compliance resources.  We will also have to establish or contract for
the  manufacture  of  products,  including  supplies  of drugs used in  clinical
trials, under the current Good Manufacturing  Practices, or cGMP, of the FDA. In
addition, the FDA may, among other things, subsequently disapprove or may recall
our product candidates that were previously approved.  We also cannot assure you
that product issues will not arise following  successful clinical trials and FDA
approval.

The rate of  completion  of clinical  trials also depends on the rate of patient
enrollment.  Patient enrollment  depends on many factors,  including the size of
the patient population, the nature of the protocol, the proximity of patients to
clinical  sites and the  eligibility  criteria for the study.  Delays in planned
patient enrollment may result in increased costs and delays,  which could have a
harmful effect on our ability to develop the products in our pipeline. If we are
unable to develop and  commercialize  products on a timely  basis or at all, our
business could be significantly and adversely affected.

                                      -8-

COMPETITION IN OUR FIELD IS INTENSE AND LIKELY TO INCREASE.

We face, and will continue to face, intense  competition from one or more of the
following entities:

     -    pharmaceutical companies;

     -    biotechnology companies;

     -    bioinformatics companies;

     -    diagnostic companies;

     -    academic and research institutions; and

     -    government agencies.

All of our products and product candidate are subject to significant competition
from organizations that are pursuing technologies and products that are the same
as or  similar  to our  technology  and  products.  Many  of  the  organizations
competing  with us have greater  capital  resources,  research  and  development
staffs and facilities and marketing capabilities.

The markets for  therapeutic and diagnostic  products that address  prostate and
bladder  cancers are large.  Our most  significant  competitors  include various
pharmaceutical  and medical device companies,  radiopharmaceutical  distributors
and biotechnology companies.

Metastron  (Strontium-89),  manufactured  by  Amerhsam  Health and  marketed  by
Galliel  Medical,  competes with Quadramet  (Samarium-153  Lexidronam).  The FDA
recently approved a generic version of Sr-89 for bone pain palliation,  which is
marketed by Bio-Nucleonics Pharma as Strontium Chloride Sr-89 Injection, USP.

A single agent,  Positron Emission  Tomography (PET),  competes with ProstaScint
(Capromab pendetide). PET imaging agent, 18-F  fluorodeoxyglucose-PET  (FDG), is
produced  and  distributed  by various  radiopharmaceutical  suppliers  (such as
PETnet and Cardinal  Health Nuclear  Pharmacy  Services).  PET (FDG) may also be
used to image  lymph  node  metastasis  in  cancer  patients,  which  may  prove
competitive  to Combidex,  following FDA approval,  if received,  and subsequent
market introduction of Combidex.

Polymedco  manufactures  BTAstat,  a point of care urine-based test approved for
monitoring bladder cancer patients.  BTAstat,  marketed by Mentor, competes with
NMP22 BladderChek (which we have licensed from Matritech). NMP22 BladderChek is,
however,  the only point of care  urine-based  test approved for both monitoring
and diagnosis of bladder  cancer.  Matritech has retained rights to market NMP22
BladderChek  directly to physicians other than urologists and oncologists,  such
as primary care physicians.

Additionally,  we face competition in the development of PSMA-related technology
and products primarily from Millenium Pharmaceuticals, Inc. and Medarex, Inc.

Before we recover  development  expenses for our products and technologies,  the
products  or  technologies  may  become  obsolete  as a result of  technological
developments  by others or us. Our products  could also be made  obsolete by new
technologies,  which are less expensive or more effective. We may not be able to
make the enhancements to our technology  necessary to compete  successfully with
newly  emerging  technologies  and  failure  to do so  could  significantly  and
adversely affect our business.

                                      -9-

WE RELY HEAVILY ON OUR COLLABORATIVE PARTNERS.

Our success  depends in significant  part upon the success of our  collaborative
partners. We have entered into the following agreements for the sale, marketing,
distribution   and   manufacture  of  our  products,   product   candidates  and
technologies:

     -    license  from  The Dow  Chemical  Company  relating  to the  Quadramet
          technology;

     -    agreement  for  manufacture  of  Quadramet  by  Bristol  Myers  Squibb
          (formerly The DuPont Pharmaceuticals Company);

     -    joint venture with Progenics  Pharmaceuticals  for the  development of
          PSMA for in vivo immunotherapy for prostate and other cancers;

     -    licensing  agreement with Molecular  Staging for technology to be used
          in  developing  in vitro  diagnostic  tests  using  PSMA and  prostate
          specific antigen, or PSA;

     -    a Supply  Agreement  with Laureate  Pharma L.P. for the  production of
          ProstaScint;

     -    an agreement with Matritech to market and distribute NMP22 BladderChek
          to urologists and oncologists in the United States;

     -    marketing, license and supply agreements with Advanced Magnetics, Inc.
          related to Combidex and Code 7228;

     -    a License  Agreement  between  our  joint  venture,  PSMA  Development
          Company LLC, and AlphaVax Human Vaccines, Inc.; and

     -    a Collaboration Agreement between our joint venture and Abgenix, Inc.

Because our collaborative partners are responsible for certain manufacturing and
distribution  activities,  among others, these activities are outside our direct
control and we rely on our partners to perform their  obligations.  For example,
Matritech  retained the ability to market its NMP22  BladderChek to primary care
physicians  and others and has begun such marketing  efforts.  In the event that
our collaborative  partners are entitled to enter into third party  arrangements
that may  economically  disadvantage us, or breach their  obligations  under our
agreements,  our products may not be commercially  successful.  As a result, any
success may be delayed and new product  development  could be inhibited with the
result that our business could be significantly and adversely affected.

OUR  BUSINESS  COULD BE HARMED IF CERTAIN  AGREEMENTS  EXPIRE OR ARE  TERMINATED
EARLY.

If our collaborative  agreements expire or are terminated and we cannot renew or
replace them on  commercially  reasonable  terms,  our  business  and  financial
results may suffer.  For example,  in January 2003, we provided  Draximage  Inc.
with  notice of our intent to  terminate  our Product  Manufacturing  and Supply
Agreement  and License  Agreement  with  Draximage  relating  to the  BrachySeed
products  which  represented  20% of our product  related  revenues for the year
ended  December 31,  2002.  In April 2003,  we entered  into an  agreement  with
Draximage formally terminating each of these agreements. We no longer market and
sell the BrachySeed products.

We are also a party to  license  agreements  under  which we have  rights to use
technologies  owned by other companies in the manufacture of our products and in


                                      -10-

our  proprietary  research,  development  and  testing  processes.  We  are  the
exclusive  licensee  of  certain  patents  and patent  applications  held by the
University of North Carolina at Chapel Hill covering part of the technology used
in the proteomics program and of certain patents and patent applications held by
the Memorial Sloan-Kettering Institute covering PSMA.

We also depend upon the  enforceability  of our  license  with The Dow  Chemical
Company with respect to Quadramet.  If the licenses were terminated,  we may not
be able to find suitable alternatives to these technologies on a timely basis or
on reasonable terms, if at all. The loss of the right to use these  technologies
that we have licensed would significantly and adversely affect our business.

WE HAVE LIMITED SALES, MARKETING AND DISTRIBUTION CAPABILITIES FOR OUR PRODUCTS.

We have  established an internal  sales force that is responsible  for marketing
and selling ProstaScint, Quadramet and NMP22 BladderChek. However, such internal
sales force has limited sales,  marketing and distribution  capabilities for our
products,  compared  to those of many of our  competitors.  Effective  August 1,
2003, we reacquired marketing rights to Quadramet from Berlex Laboratories, Inc.
in North and Latin  America,  for an  upfront  payment of $8.0  million  and the
obligation  to pay  royalties  to Berlex on future  sales of  Quadramet.  If our
internal sales force is unable to successfully  market  Quadramet,  our business
and financial condition may be adversely affected. If we are unable to establish
and maintain  significant sales,  marketing and distribution  efforts within the
United States, either internally or through arrangements with third parties, our
business may be significantly  and adversely  affected.  In locations outside of
the United States, we have not established a selling presence.

THERE ARE RISKS ASSOCIATED WITH THE MANUFACTURE AND SUPPLY OF OUR PRODUCTS.

If we are to be  successful,  our  products  will  have  to be  manufactured  by
contract  manufacturers in compliance with regulatory  requirements and at costs
acceptable to us. If we are unable to  successfully  arrange for the manufacture
of our products and product candidates,  either because potential  manufacturers
are not cGMP compliant,  are not available or charge excessive amounts,  we will
not be able to successfully  commercialize our products and our business will be
significantly and adversely affected.

ProstaScint was manufactured at a cGMP compliant manufacturing facility operated
by  Laureate  Pharma  L.P.  (formerly  Bard  BioPharma  L.P.).  We had access to
Laureate's  facility for  continued  manufacturing  of the product until January
2002.  We  entered  into a  Development  and  Manufacturing  Agreement  with DSM
Biologics  Company  B.V.  in July 2000,  which we  intended  would  replace  our
arrangement with Laureate with respect to ProstaScint. Our relationship with DSM
has  subsequently  terminated.  We  entered  into a new  Contract  Manufacturing
Agreement  with Laureate  Pharma L.P. in January 2003. Our failure to maintain a
long term supply agreement on commercially reasonable terms will have a material
adverse effect on our business, financial condition and results of operations.

Quadramet is  manufactured  by  Bristol-Myers  Squibb (BMS)  (formerly  DuPont),
pursuant  to  an  agreement   with  Cytogen.   Some   components  of  Quadramet,
particularly  Samarium153 and EDTMP,  are provided to BMS by outside  suppliers.
Due to radioactive  decay,  Samarium153  must be produced on a weekly basis. BMS
obtains its requirements for Samarium153 from one supplier.  Alternative sources
for  these  components  may  not be  readily  available.  If BMS  cannot  obtain
sufficient quantities of the components on commercially  reasonable terms, or in
a timely  manner,  it would be unable to  manufacture  Quadramet on a timely and
cost-effective  basis,  which  could  have  a  material  adverse  effect  on our
business, financial condition and results of operations.

Pursuant to the terms of our distribution  agreement with Matritech,  we rely on
Matritech as the sole supplier of NMP22 BladderChek.  Matritech uses independent
contractors to manufacture  the product.  If Matritech fails to, or is unable to

                                      -11-

provide  the  product,  we could  experience  a material  adverse  effect on our
business, financial condition and results of operations.

The Company, our contract manufacturers and testing laboratories are required to
adhere to United  States Food & Drug  Administration  regulations  setting forth
requirements for cGMP, and similar regulations in other countries, which include
extensive testing,  control and documentation  requirements.  Ongoing compliance
with cGMP,  labeling and other applicable  regulatory  requirements is monitored
through  periodic  inspections  and  market  surveillance  by state and  federal
agencies,  including  the FDA, and by  comparable  agencies in other  countries.
Failure of our  contract  vendors or us to comply  with  applicable  regulations
could result in sanctions  being imposed on us,  including  fines,  injunctions,
civil  penalties,  failure of the  government  to grant  premarket  clearance or
premarket  approval of drugs,  delays,  suspension  or  withdrawal of approvals,
seizures  or  recalls  of   products,   operating   restrictions   and  criminal
prosecutions any of which could significantly and adversely affect our business.

FAILURE OF CONSUMERS TO OBTAIN ADEQUATE  REIMBURSEMENT  FROM THIRD-PARTY  PAYORS
COULD LIMIT MARKET ACCEPTANCE AND AFFECT PRICING OF OUR PRODUCTS.

Our business,  financial condition and results of operations will continue to be
affected by the efforts of governments and other  third-party  payors to contain
or reduce the costs of  healthcare.  There have been,  and we expect  that there
will  continue  to be, a number of  federal  and state  proposals  to  implement
government  control of pricing and  profitability  of therapeutic and diagnostic
imaging  agents such as our products.  In addition,  an emphasis on managed care
increases  possible  pressure  on  pricing  of these  products.  While we cannot
predict whether these  legislative or regulatory  proposals will be adopted,  or
the effects  these  proposals or managed care efforts may have on our  business,
the  announcement  of these  proposals  and the  adoption of these  proposals or
efforts  could affect our stock price or our  business.  Further,  to the extent
these  proposals or efforts have an adverse  effect on other  companies that are
our prospective corporate partners, our ability to establish necessary strategic
alliances may be harmed.

Sales of our  products  depend in part on  reimbursement  to the  consumer  from
third-party payors,  including  Medicare,  Medicaid and private health insurance
plans.  Third-party  payors are increasingly  challenging the prices charged for
medical products and services. If third-party payors determine that our products
are  not  cost-effective,  they  may  discontinue  reimbursement  to  consumers.
Alternatively,  such reimbursement may not be sufficient to allow us to sell our
products on a competitive basis. Approval of our products for reimbursement by a
third-party  payor may  depend on a number of  factors,  including  the  payor's
determination  that our  products  are  clinically  useful  and  cost-effective,
medically  necessary and not experimental or  investigational.  Reimbursement is
determined by each payor  individually and in specific cases. The  reimbursement
process  can  be  time  consuming.  If we  cannot  secure  adequate  third-party
reimbursement  for  our  products,  our  business  could  be  significantly  and
adversely affected.

IF WE ARE UNABLE TO COMPLY WITH APPLICABLE GOVERNMENTAL REGULATION WE MAY NOT BE
ABLE TO CONTINUE OUR OPERATIONS.

Any products tested, manufactured or distributed by us or on our behalf pursuant
to FDA approvals are subject to pervasive and continuing  regulation by numerous
regulatory authorities, including primarily the FDA. We may be slow to adapt, or
we may never  adapt to changes  in  existing  requirements  or  adoption  of new
requirements  or policies.  Our failure to comply with  regulatory  requirements
could subject us to enforcement  action,  including product  seizures,  recalls,
withdrawal,   suspension,  or  revocation  of  approvals,   restrictions  on  or
injunctions  against  marketing our products based on our technology,  and civil
and criminal  penalties.  We may incur significant costs to comply with laws and
regulations in the future or compliance  with laws or regulations  may create an
unsustainable burden on our business.

                                      -12-

Numerous federal, state and local governmental authorities, principally the FDA,
and similar  regulatory  agencies in other  countries,  regulate the preclinical
testing,  clinical trials,  manufacture and promotion of any compounds or agents
we or our collaborative partners develop, and the manufacturing and marketing of
any resulting drugs. The product  development and regulatory approval process is
lengthy, expensive, uncertain and subject to delays.

The regulatory risks we face also include the following:

     -    any compound or agent we or our  collaborative  partners  develop must
          receive regulatory agency approval before it may be marketed as a drug
          in a particular country;

     -    the  regulatory  process,   which  includes  preclinical  testing  and
          clinical  trials of each  compound or agent in order to establish  its
          safety and  efficacy,  varies from  country to country,  can take many
          years and requires the expenditure of substantial resources;

     -    in all  circumstances,  approval of the use of  previously  unapproved
          radioisotopes in certain of our products  requires  approval of either
          the Nuclear  Regulatory  Commission  or  equivalent  state  regulatory
          agencies,  which  may  be a  lengthy  process.  A  radioisotope  is an
          unstable form of an element which undergoes radioactive decay, thereby
          emitting radiation which may be used, for example, to image or destroy
          harmful growths or tissue;

     -    data obtained from preclinical and clinical activities are susceptible
          to  varying  interpretations  which  could  delay,  limit  or  prevent
          regulatory agency approval; and

     -    delays  or  rejections  may  be  encountered  based  upon  changes  in
          regulatory  agency  policy  during the  period of product  development
          and/or the period of review of any application  for regulatory  agency
          approval.  These delays could  adversely  affect the  marketing of any
          products  we or our  collaborative  partners  develop,  impose  costly
          procedures upon our activities, diminish any competitive advantages we
          or our  collaborative  partners  may attain and  adversely  affect our
          ability to receive royalties.

Regulatory  agency  approval  for a product or agent may not be received and may
entail  limitations on the indicated uses that could limit the potential  market
for any such  product.  For  example,  as  disclosed  in our press  releases and
periodic filings,  we have exclusive United States marketing rights to Combidex,
an ultrasmall superparamagnetic iron oxide contrast agent for magnetic resonance
imaging of lymph nodes,  that is pending clearance by the United States Food and
Drug  Administration.  In June 2000,  Advanced  Magnetics received an approvable
letter  from  the  FDA  with  respect  to  Combidex.  We  are  awaiting  further
information from the FDA regarding Combidex.

Furthermore, if and when such approval is obtained, the marketing,  manufacture,
labeling,  packaging,  reporting,  storage, advertising and promotion and record
keeping  related to our products  would remain  subject to extensive  regulatory
requirements.  Discovery  of  previously  unknown  problems  with  a  drug,  its
manufacture  or its  manufacturer  may  result  in  restrictions  on such  drug,
manufacture or manufacturer,  including  withdrawal of the drug from the market.
Failure  to  comply  with  regulatory   requirements   could  result  in  fines,
injunctions,   seizures,   recalls,   suspension  or  withdrawal  of  regulatory
approvals, operating restrictions and criminal prosecution.

The United States Food, Drug and Cosmetics Act requires (i) that our products be
manufactured in FDA registered  facilities subject to inspection,  and (ii) that
we  comply  with  cGMP,  which  imposes  certain  procedural  and  documentation
requirements   upon  us  and  our   manufacturing   partners   with  respect  to
manufacturing and quality assurance  activities.  If we or our contract partners
do not  comply  with  cGMP we may be  subject  to  sanctions,  including  fines,

                                      -13-

injunctions,  civil penalties, recalls or seizures of products, total or partial
suspension of production,  product  recalls,  failure of the government to grant
premarket  clearance or premarket  approval for drugs,  withdrawal  of marketing
approvals and criminal prosecution.

WE COULD BE NEGATIVELY  IMPACTED BY FUTURE  INTERPRETATION  OR IMPLEMENTATION OF
FEDERAL  AND STATE  FRAUD AND ABUSE  LAWS,  INCLUDING  ANTI-KICKBACK  LAWS,  THE
FEDERAL STARK LAW AND OTHER FEDERAL AND STATE ANTI-REFERRAL LAWS.

We are subject to various federal and state laws pertaining to health care fraud
and  abuse,  including  anti-kickback  laws and  physician  self-referral  laws.
Violations  of these laws are  punishable  by criminal  and/or civil  sanctions,
including,  in some instances,  imprisonment and exclusion from participation in
federal  and state  health  care  programs,  including  Medicare,  Medicaid  and
Veterans  Administration  health  programs.  We have  not been  challenged  by a
governmental  authority  under any of these laws and believe that our operations
are in compliance with such laws. However, because of the far-reaching nature of
these laws,  we may be required to alter one or more of our  practices  to be in
compliance with these laws.  Health care fraud and abuse regulations are complex
and even minor,  inadvertent  irregularities can potentially give rise to claims
that the statute has been violated. Any violations of these laws could result in
a material  adverse effect on our business,  financial  condition and results of
operations.  If  there is a  change  in law,  regulation  or  administrative  or
judicial  interpretations,  we may have to change our business  practices or our
existing business practices could be challenged as unlawful,  which could have a
material  adverse  effect on our  business,  financial  condition and results of
operations.

We could become subject to false claims litigation under federal statutes, which
can lead to civil  money  penalties,  criminal  fines and  imprisonment,  and/or
exclusion from  participation in Medicare,  Medicaid and other federal and state
health care programs.  These false claims statutes include the False Claims Act,
which allows any person to bring suit alleging false or fraudulent  claims under
federal  programs or contracts  claims or other violations of the statute and to
share  in any  amounts  paid  by  the  entity  to the  government  in  fines  or
settlement.  Such suits, known as qui tam actions, have increased  significantly
in recent years and have increased the risk that a health care company,  such as
us, will have to defend a false claim action,  pay fines or be excluded from the
Medicare  program,  Medicaid  programs or other  federal  and state  health care
programs as a result of an investigation  arising out of such action.  If we are
unsuccessful  in  defending  against  any such  action,  such  action may have a
material  adverse  effect on our  business,  financial  condition and results of
operations.

WE DEPEND ON ATTRACTING AND RETAINING KEY PERSONNEL.

We are  highly  dependent  on  the  principal  members  of  our  management  and
scientific  staff.  The  loss of their  services  might  significantly  delay or
prevent the  achievement  of development  or strategic  objectives.  Our success
depends  on our  ability  to retain  key  employees  and to  attract  additional
qualified employees.  Competition for personnel is intense, and therefore we may
not be able to retain existing personnel or attract and retain additional highly
qualified employees in the future.

During 2002, we announced  numerous changes to members of our senior management.
H. Joseph Reiser,  Ph.D. who held the position of President and Chief  Executive
Officer of the Company from April 1998 until  December  2002,  resigned from his
position for personal reasons.  Michael D. Becker,  our former Vice President of
Business Development, was unanimously elected by our board of directors to serve
as Dr. Reiser's replacement as President and Chief Executive Officer. Mr. Becker
was also unanimously elected to serve on our Board of Directors.  Dr. Reiser has
remained a member of our Board of Directors.  In addition,  Lawrence R. Hoffman,
our Vice President and Chief Financial Officer since July 2000, left the Company

                                      -14-

to pursue  other  opportunities  as of  December  31,  2002.  Ms. Thu Dang,  our
Director of Finance, was subsequently promoted to Vice President of Finance.

Additionally,  in the first  quarter of 2003:  (i) William  Goeckeler,  our Vice
President  of  Research  and   Development   was  promoted  to  Vice  President,
Operations;  (ii) Deborah  Kaminsky,  our Vice President of Sales and Marketing,
shifted her work focus, and serves as our Vice President,  Business Development;
(iii)  Rita  Auld,  our  Director  of  Human  Resources,  was  promoted  to Vice
President,  Human Resources and  Administration  and Corporate  Secretary;  (iv)
Corey Jacklin assumed the  responsibilities of Senior Director of Sales; and (v)
June Gobern was promoted to Senior Director of Marketing.

On December 17, 2002, we entered into a letter  agreement with Michael D. Becker
in  connection  with Mr.  Becker's  promotion to President  and Chief  Executive
Officer of the Company.  Under the terms of such letter  agreement,  Mr.  Becker
receives an annual  base  salary of  $250,000.  Mr.  Becker is also  eligible to
participate  in  our  Cytogen  Corporation  Performance  Bonus  Plan,  as and if
approved  by our Board of  Directors,  with a target  bonus  rate of 30% of base
salary based upon  performance  objectives.  Mr.  Becker is also entitled to all
existing Company benefits, at the sole discretion of the Board of Directors.  In
addition,  Mr.  Becker was  granted  options to purchase  200,000  shares of our
common  stock  under our 1995 Stock  Option  Plan.  Pursuant to the terms of the
letter agreement,  in the event we terminate Mr. Becker's employment for reasons
other than for cause,  as defined  therein,  Mr.  Becker  shall be  entitled  to
receive twelve month's base pay and  continuation of benefits under COBRA, and a
pro  rata  portion  of  any  incentive  benefits  earned  through  the  date  of
termination.

Each of our  executive  officers is currently  party to an  Executive  Change of
Control Severance Agreement with Cytogen.  Such agreements  provide,  generally,
for the  payment of twelve  months'  base  salary,  a  pro-rata  portion of such
officer's  bonus  compensation,  the  continuation  of all benefits,  reasonable
Company-paid  outplacement  assistance and certain other accrued rights,  in the
event such officer's employment with us is terminated in connection with certain
changes in control.

We do not carry key person life insurance policies and we do not typically enter
into long-term arrangements with our key personnel. If we are unable to hire and
retain  personnel in key  positions,  our business  could be  significantly  and
adversely affected unless qualified replacements can be found.

OUR  BUSINESS  EXPOSES  US TO  POTENTIAL  LIABILITY  CLAIMS  THAT MAY EXCEED OUR
FINANCIAL  RESOURCES,  INCLUDING  OUR  INSURANCE  COVERAGE,  AND MAY LEAD TO THE
CURTAILMENT OR TERMINATION OF OUR OPERATIONS.

Our  business is subject to product  liability  risks  inherent in the  testing,
manufacturing  and marketing of our products and product liability claims may be
asserted  against us, our  collaborators  or our  licensees.  While we currently
maintain  product  liability  insurance  in the  amount of $10.0  million,  such
coverage  may not be adequate  to protect us against  future  product  liability
claims. In addition,  product liability  insurance may not be available to us in
the future on commercially reasonable terms, if at all. Although we have not had
a history of claims  payments  that have  exceeded  our  insurance  coverage  or
available  financial  resources,  if  liability  claims  against  us exceed  our
financial resources or coverage amounts, we may have to curtail or terminate our
operations.  In addition,  while we currently  maintain  directors  and officers
liability  insurance in the amount of $20.0  million,  such  coverage may not be
available on  commercially  reasonable  terms or be adequate to cover any claims
that we may be  required  to satisfy in the future.  Our  insurance  coverage is
subject to industry standard and certain other limitations.

OUR BUSINESS INVOLVES ENVIRONMENTAL RISKS THAT MAY RESULT IN LIABILITY.

We are subject to a variety of local,  state,  federal  and  foreign  government
regulations  relating to storage,  discharge,  handling,  emission,  generation,
manufacture and disposal of toxic, infectious or other hazardous substances used

                                      -15-

to manufacture  our products.  If we fail to comply with these  regulations,  we
could be liable  for  damages,  penalties,  or other  forms of  censure  and our
business  could be  significantly  and adversely  affected.  We currently do not
carry  insurance  for  contamination  or injury  resulting  from the use of such
materials.

Two of our marketed  products,  ProstaScint  and Quadramet  utilize  radioactive
materials.  ProstaScint is not manufactured or shipped as a radioactive material
because the radioactive  component is not added until the product has arrived at
its  final  destination  (a   radiopharmacy).   Laureate  Pharma,  the  contract
manufacturer of ProstaScint,  holds a radioactive materials license because such
license is required for certain release and stability tests of the product.

Quadramet,  however, is manufactured and shipped as radioactive,  and therefore,
the  manufacturing and distribution of this product must comply with regulations
promulgated  by the U.S.  Nuclear  Regulatory  Commission.  Bristol Myers Squibb
manufacturers and distributes  Quadramet,  and is,  therefore,  subject to these
regulations.

OUR INTELLECTUAL PROPERTY IS DIFFICULT TO PROTECT.

Our business and competitive positions are dependent upon our ability to protect
our  proprietary  technology.  Because  of the  substantial  length  of time and
expense  associated with  development of new products,  we, like the rest of the
biopharmaceutical  industry,  place  considerable  importance  on obtaining  and
maintaining  patent and trade secret protection for new  technologies,  products
and  processes.  We  have  filed  patent  applications  for our  technology  for
diagnostic  and  therapeutic  products and the methods for their  production and
use.

The patent  positions of  pharmaceutical,  biopharmaceutical  and  biotechnology
companies,  including us, are generally  uncertain and involve complex legal and
factual questions.  Our patent applications may not protect our technologies and
products because, among other things:

     -    there is no guarantee that any of our pending patent applications will
          result in issued patents;

     -    we may  develop  additional  proprietary  technologies  that  are  not
          patentable;

     -    there is no guarantee that any patents issued to us, our collaborators
          or our  licensors  will  provide  a basis  for a  commercially  viable
          product;

     -    there  is  no  guarantee   that  any  patents  issued  to  us  or  our
          collaborators will provide us with any competitive advantage;

     -    there  is  no  guarantee   that  any  patents  issued  to  us  or  our
          collaborators  will not be challenged,  circumvented or invalidated by
          third parties; and

     -    there is no guarantee that any patents  previously issued to others or
          issued in the future will not have an adverse effect on our ability to
          do business.

In  addition,  patent  law in the  technology  fields  in  which we  operate  is
uncertain and still evolving,  the degree of protection that may be afforded any
patents we are issued or license  from others may not be  sufficient  to protect
our commercial interests.  Furthermore, others may independently develop similar
or  alternative  technologies,  duplicate our  technologies,  or, if patents are
issued to us, design around the patented technologies  developed by us. We could
incur  substantial costs in litigation if we are required to defend ourselves in
patent suits by third  parties or if we initiate  such suits.  In  addition,  if
challenged by others in litigation, the patents we have been issued, or which we
have been assigned or we have licensed from others may be found  invalid.  It is

                                      -16-

also possible that our activities may infringe patents owned by others.  Defense
and  prosecution  of patent  matters can be expensive  and  time-consuming  and,
regardless  of  whether  the  outcome  is  favorable  to us,  can  result in the
diversion of substantial financial,  managerial and other resources.  An adverse
outcome could:

     -    subject us to significant liability to third parties;

     -    require us to cease any related  research and  development  activities
          and product sales; or

     -    require us to obtain licenses from third parties.

Any licenses required under any such third-party  patents or proprietary  rights
may not be available on commercially  reasonable terms, if at all. Moreover, the
laws of certain  countries  may not protect our  proprietary  rights to the same
extent as the laws of the United States.  We cannot  predict  whether our or our
competitors'  pending patent  applications  will result in the issuance of valid
patents which may significantly and adversely affect our business.

OUR SECURITY MEASURES MAY NOT PROTECT OUR UNPATENTED PROPRIETARY TECHNOLOGY.

We also rely upon  trade  secret  protection  for some of our  confidential  and
proprietary  information that is not subject matter for which patent  protection
is available. To help protect our rights, we require all employees, consultants,
advisors and collaborators to enter into confidentiality agreements that require
disclosure,  and in most cases, assignment to us, of their ideas,  developments,
discoveries  and  inventions,  and that prohibit the disclosure of  confidential
information  to anyone  outside  Cytogen or our  subsidiaries.  Although  we are
unaware of any  unauthorized  use or  disclosure of our  unpatented  proprietary
technology to date, these agreements may not provide adequate protection for our
trade  secrets,  know-how  or other  proprietary  information  or  prevent  such
unauthorized use or disclosure.

WE ARE CURRENTLY SUBJECT TO PATENT LITIGATION.

On March 17,  2000,  we were  served with a  complaint  filed  against us in the
United  States  District  Court  for the  District  of New  Jersey  by M.  David
Goldenberg  ("Goldenberg") and Immunomedics,  Inc. (collectively  "Plaintiffs").
The  litigation   claims  that  our  ProstaScint   product  infringes  a  patent
purportedly  owned by Goldenberg and licensed to  Immunomedics.  We believe that
ProstaScint  does not infringe  this patent,  and that the patent is invalid and
unenforceable.  The  patent  sought to be  enforced  in the  litigation  has now
expired;  as a result,  the claim,  even if  successful,  would not result in an
injunction  barring the continued sale of ProstaScint or affect any other of our
products or technology.  In addition,  we have certain rights to indemnification
against litigation and litigation  expenses from the inventor of technology used
in  ProstaScint,  which  may be  offset  against  royalty  payments  on sales of
ProstaScint.  However, given the uncertainty associated with litigation,  we may
incur material  expenditures.  On December 17, 2001,  Cytogen filed a motion for
summary   judgment  of   non-infringement   of  the   asserted   claims  of  the
patent-in-suit.   The  Plaintiffs  opposed  that  motion  and  filed  their  own
cross-motion for summary  judgment of  infringement.  On July 3, 2002, the Court
denied both parties' summary judgment motions, with leave to renew those motions
after presenting  expert testimony and legal argument based upon that testimony.
The parties  subsequently  presented expert  testimony and submitted  additional
briefing. On April 29, 2003, our motion for summary judgment of non-infringement
of all asserted claims was granted,  plaintiffs'  motion for summary judgment of
infringement  was  denied  and the case was  ordered  closed.  On May 12,  2003,
Plaintiffs filed a Notice of Appeal regarding this decision to the U.S. Court of
Appeals for the Federal Circuit and subsequently  filed such appeal on August 4,
2003.

                                      -17-

OUR STOCK PRICE HAS BEEN AND MAY CONTINUE TO BE VOLATILE, AND YOUR INVESTMENT IN
OUR STOCK COULD DECLINE IN VALUE OR FLUCTUATE SIGNIFICANTLY.

The market prices for securities of biotechnology and  pharmaceutical  companies
have  historically  been highly  volatile,  and the market has from time to time
experienced  significant price and volume fluctuations that are unrelated to the
operating  performance of particular  companies.  The market price of our common
stock has fluctuated over a wide range and may continue to fluctuate for various
reasons, including, but not limited to, announcements concerning our competitors
or us regarding:

     -    results of clinical trials;

     -    technological innovations or new commercial products;

     -    changes in  governmental  regulation  or the status of our  regulatory
          approvals or applications;

     -    changes in earnings;

     -    changes in health care policies and practices;

     -    developments or disputes concerning proprietary rights;

     -    litigation  or  public  concern  as to  safety  of the  our  potential
          products; and

     -    changes in general market conditions.

These  fluctuations may be exaggerated if the trading volume of our common stock
is low. These  fluctuations  may or may not be based upon any of our business or
operating results. Our common stock may experience similar or even more dramatic
price and volume fluctuations which may continue indefinitely.

The following table sets forth the high and low sale prices for our common stock
for each of the quarters in the period  beginning  July 1, 2000 through June 30,
2003  as  reported  on the  Nasdaq  National  Market,  and as  adjusted  for our
one-for-ten reverse stock split effected October 25, 2002:

   Quarter Ended                   High                   Low
   -------------                   ----                   ---

September 30, 2000               $113.75                 $55.00
December 31, 2000                 $71.88                 $20.00
March 31, 2001                    $65.63                 $23.13
June 30, 2001                     $61.00                 $21.88
September 30, 2001                $53.90                 $19.00
December 31, 2001                 $45.50                 $20.50
March 31, 2002                    $34.70                 $21.10
June 30, 2002                     $22.40                  $9.10
September 30, 2002                $11.50                  $3.20
December 31, 2002                  $8.44                  $2.68
March 31, 2003                     $3.90                  $2.51
June 30, 2003                      $8.60                  $2.80

                                      -18-

WE HAVE ADOPTED  VARIOUS  ANTI-TAKEOVER  PROVISIONS  WHICH MAY AFFECT THE MARKET
PRICE OF OUR COMMON STOCK AND PREVENT OR FRUSTRATE  ATTEMPTS BY OUR STOCKHOLDERS
TO REPLACE OR REMOVE OUR MANAGEMENT TEAM.

Our Board of Directors has the authority,  without further action by the holders
of common stock, to issue from time to time, up to 5,400,000 shares of preferred
stock in one or more classes or series, and to fix the rights and preferences of
the  preferred  stock.  Pursuant  to these  provisions,  we have  implemented  a
stockholder  rights plan by which one preferred stock purchase right is attached
to each share of common stock, as a means to deter coercive takeover tactics and
to prevent an acquirer  from  gaining  control of us without  some  mechanism to
secure a fair price for all of our stockholders if an acquisition was completed.
These  rights  will be  exercisable  if a person  or group  acquires  beneficial
ownership  of 20% or more of our  common  stock and can be made  exercisable  by
action of our board of directors  if a person or group  commences a tender offer
which would  result in such person or group  beneficially  owning 20% or more of
our common stock.  Each right will entitle the holder to buy one  one-thousandth
of a share of a new series of our junior participating  preferred stock for $20.
If any person or group becomes the beneficial owner of 20% or more of our common
stock (with certain  limited  exceptions),  then each right not owned by the 20%
stockholder  will  entitle its holder to  purchase,  at the right's then current
exercise price, common shares having a market value of twice the exercise price.
In addition,  if after any person has become a 20% stockholder,  we are involved
in a merger or other business combination  transaction with another person, each
right will entitle its holder (other than the 20%  stockholder) to purchase,  at
the right's then current exercise price,  common shares of the acquiring company
having a value of twice the right's then current exercise price.

We are subject to provisions of Delaware corporate law which, subject to certain
exceptions,  will prohibit us from engaging in any "business combination" with a
person who,  together with  affiliates and  associates,  owns 15% or more of our
common stock for a period of three years following the date that the person came
to own 15% or more of our  common  stock  unless  the  business  combination  is
approved in a prescribed manner.

These   provisions  of  the   stockholder   rights  plan,  our   certificate  of
incorporation, and of Delaware law may have the effect of delaying, deterring or
preventing a change in control of Cytogen,  may  discourage  bids for our common
stock at a premium over market price and may adversely  affect the market price,
and the  voting  and other  rights  of the  holders,  of our  common  stock.  In
addition,  these  provisions  make it more  difficult  to  replace or remove our
current  management team in the event our stockholders  believe this would be in
the best interest of the Company and our stockholders.

THE LIQUIDITY OF OUR COMMON STOCK COULD BE ADVERSELY AFFECTED IF WE ARE DELISTED
FROM THE NASDAQ NATIONAL MARKET.

On August 14, 2002,  we announced  that we had  received  notification  from the
Nasdaq  Stock  Market,  Inc.  that our common stock had closed below the minimum
$1.00 per share  requirement  for the  previous 30  consecutive  trading days as
required under Marketplace Rule 4450(a)(5).  In accordance with Marketplace Rule
4450 (e)(2), we were provided with 90 calendar days, or until November 12, 2002,
to regain compliance by having the bid price for our common stock close at $1.00
or greater for a minimum period of 10 consecutive trading days.

On September  26, 2002,  we  announced  that our Board of Directors  unanimously
approved,  and recommended to our  stockholders,  a proposal that would give the
Board of  Directors  authority  to effect a reverse  stock  split of our  common
stock, at a ratio of up to one-for-ten at any time prior to December 31, 2002. A
special  meeting of our  stockholders  was held on October  25, 2002 to consider
such recommendation. Pursuant to the authority granted to our Board of Directors

                                      -19-

at the special  meeting,  on October 25,  2002,  we  implemented  a  one-for-ten
reverse split of our outstanding and authorized shares of common stock.

We subsequently achieved compliance with Nasdaq Marketplace Rule 4450(a)(5), and
received a letter from Nasdaq  notifying us of such  compliance  on November 11,
2002.

If we do not continue to maintain  compliance with this Marketplace Rule, or any
other Listing  Standards which may apply to us, we may once again face delisting
from the Nasdaq National Market in the future.

In the event that we are unable  maintain  compliance  with all relevant  Nasdaq
Listing  Standards,  our  securities may be subject to delisting from the Nasdaq
National Market. If such delisting occurs, the market price and market liquidity
of our common stock may be adversely affected.

Alternatively,  if faced with such  delisting,  we may submit an  application to
transfer  the listing of our common  stock to the Nasdaq  SmallCap  Market.  The
Nasdaq SmallCap Market also has a $1.00 minimum bid price requirement.

If our common stock is delisted by Nasdaq, our common stock would be eligible to
trade on the OTC Bulletin Board maintained by Nasdaq,  another  over-the-counter
quotation  system,  or on the pink  sheets  where an  investor  may find it more
difficult to dispose of or obtain accurate  quotations as to the market value of
our common stock. In addition,  we would be subject to a rule promulgated by the
Securities and Exchange  Commission  that, if we fail to meet criteria set forth
in such rule,  imposes various practice  requirements on broker-dealers who sell
securities governed by the rule to persons other than established  customers and
accredited  investors.  Consequently,  such rule may deter  broker-dealers  from
recommending or selling our common stock, which may further affect the liquidity
of our common stock.

Delisting  from Nasdaq will make  trading our common  stock more  difficult  for
investors,  potentially leading to further declines in our share price. It would
also make it more difficult for us to raise additional  capital.  Further, if we
are delisted we would also incur  additional  costs under state blue sky laws in
connection with any sales of our securities.  These  requirements could severely
limit  the  market  liquidity  of  our  common  stock  and  the  ability  of our
shareholders to sell our common stock in the secondary market.

A LARGE NUMBER OF OUR SHARES ARE  ELIGIBLE  FOR FUTURE SALE WHICH MAY  ADVERSELY
IMPACT THE MARKET PRICE OF OUR COMMON STOCK.

A large number of shares of our common stock are already  outstanding,  issuable
upon exercise of options and warrants,  or the achievement of certain milestones
under previously  completed  acquisitions and may be eligible for resale,  which
may adversely  affect the market price of our common stock.  As of June 18, 2003
we had 9,818,755 shares of common stock outstanding, which number of shares: (i)
includes  an  aggregate  of 241  shares  of  common  stock to be issued to prior
holders of  securities  of CytoRad  Incorporated  and  Cellcor,  Inc.,  which we
acquired in 1995, upon each such holders respective exchange of such securities;
(ii)  excludes  50,000  shares  of  common  stock  previously  issued  by us and
currently held in escrow pending release,  upon certain conditions,  to Advanced
Magnetics, who currently maintains voting control of such securities;  and (iii)
excludes 28,589 shares  previously  issued by us and currently held for issuance
by the  custodian  of our  Employee  Stock  Purchase  Plan  to the  participants
thereunder,  in the event they elect to  purchase  such  shares.  An  additional
392,715  shares of common  stock are issuable  upon the exercise of  outstanding
stock options and an additional 422,153 shares of common stock are issuable upon
the exercise of  outstanding  warrants,  including  the  warrants  issued to the
selling  stockholders  in this  prospectus.  Substantially  all of  such  shares
subject to  outstanding  options and warrants  will,  when issued upon  exercise
thereof, be available for immediate resale in the public market pursuant to

                                      -20-

either a currently effective  registration statement under the Securities Act of
1933, as amended, or pursuant to Rule 144 or Rule 701 promulgated thereunder. In
addition,  there are 167,951  additional  shares of common  stock  reserved  for
future issuance under our current stock options plans,  3,630 additional  shares
of  common  stock  reserved  for  issuance  under  our  401(k)  Plan and  22,751
additional  shares of common stock  reserved for the future  issuance  under our
employee  bonus plan.  All such reserved  shares have been  registered  with the
Securities and Exchange Commission pursuant to currently effective  registration
statements.  In addition,  there are 95,153  additional  shares of common stock,
subject to certain adjustments,  reserved for future issuance in connection with
the issuance of a convertible promissory note, having a seven (7) year maturity,
to ELAN Corporation, plc in August 1998.

In connection  with our  acquisition of Prostagen,  Inc. in June 1999, we issued
205,000  unregistered  shares of our common  stock to the then  stockholders  of
Prostagen, which shares may be sold from time to time pursuant to Rule 144 under
the Securities Act. Such stockholders  also have certain piggyback  registration
rights with  respect to these  shares of common  stock.  An  additional  127,699
shares  have  been  issued  in  2002  and  were  subsequently  registered  on  a
registration  statement on Form S-3. An additional $2.0 million worth of Cytogen
common stock,  which we are obligated to register  under the  Securities  Act of
1933, as amended,  may be issued if certain  milestones are achieved in the PSMA
development programs.

On October 25, 2001,  we filed with the  Securities  and  Exchange  Commission a
shelf registration statement on Form S-3 covering 1,000,000 shares of our common
stock. 297,066 and 416,670 of such registered shares were issued to the State of
Wisconsin  Investment Board in private offering  transactions in each of January
2002 and June 2002, respectively.

Availability  of a significant  number of additional  shares of our common stock
for future sale and issuance could depress the price of our common stock.

BECAUSE WE DO NOT INTEND TO PAY,  AND HAVE NOT PAID,  ANY CASH  DIVIDENDS ON OUR
SHARES OF COMMON STOCK, OUR STOCKHOLDERS WILL NOT BE ABLE TO RECEIVE A RETURN ON
THEIR SHARES UNLESS THE VALUE OF OUR SHARES APPRECIATES AND THEY SELL THEM.

We have never paid or declared  any cash  dividends on our common stock or other
securities and intend to retain any future  earnings to finance the  development
and expansion of our business. We do not anticipate paying any cash dividends on
our common stock in the foreseeable future. Therefore, our stockholders will not
be able to  receive  a return on their  shares  unless  the value of our  shares
appreciates and they sell them.

                                      -21-



                SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

         This  prospectus  includes or incorporates  forward-looking  statements
within the meaning of Section 27A of the  Securities Act of 1933 and Section 21E
of the Securities Exchange Act of 1934, as amended.  All statements,  other than
statements of historical  facts,  included or  incorporated  in this  prospectus
regarding our strategy, future operations,  financial position, future revenues,
projected   costs,   prospects,   plans  and   objectives  of   management   are
forward-looking  statements.  The words "anticipates,"  "believes," "estimates,"
"expects,"  "intends," "may," "plans,"  "projects,"  "will," "would" and similar
expressions are intended to identify  forward-looking  statements,  although not
all  forward-looking  statements  contain  these  identifying  words.  We cannot
guarantee  that we actually will achieve the plans,  intentions or  expectations
disclosed  in our  forward-looking  statements  and you should  not place  undue
reliance  on our  forward-looking  statements.  Actual  results or events  could
differ materially from the plans,  intentions and expectations  disclosed in the
forward-looking  statements we make. We have included  important  factors in the
cautionary statements included or incorporated in this prospectus,  particularly
under the heading "Risk Factors",  that we believe could cause actual results or
events to differ  materially from the  forward-looking  statements that we make.
Our forward-looking statements do not reflect the potential impact of any future
acquisitions,  mergers, dispositions, joint ventures or investments we may make.
We do not assume any obligation to update any  forward-looking  statements.  You
should not unduly rely on forward-looking  statements  contained or incorporated
by  reference  in  this  prospectus.  Actual  results  or  outcomes  may  differ
materially  from those  predicted in our  forward-looking  statements due to the
risks and uncertainties inherent in our business.

         You should read and interpret any  forward-looking  statements together
with the following documents:

     -    our most recent Annual Report on Form 10-K, as amended;

     -    our most recent quarterly report of Form 10-Q;

     -    the risk factors  contained in this prospectus under the caption "Risk
          Factors"; and

     -    our other filings with the Securities and Exchange Commission.

         Any forward-looking  statement speaks only as of the date on which that
statement is made. We will not update any  forward-looking  statement to reflect
events or  circumstances  that occur after the date on which such  statement  is
made.

                                 USE OF PROCEEDS

         We will not receive any proceeds from the sale of shares by the selling
stockholders.

         The  selling  stockholders  will  pay any  underwriting  discounts  and
commissions  and expenses  incurred by the selling  stockholders  for brokerage,
accounting,  tax or legal services or any other expenses incurred by the selling
stockholders in disposing of the shares.  We will bear all other costs, fees and
expenses  incurred in effecting the  registration  of the shares covered by this
prospectus,  including,  without  limitation,  all registration and filing fees,
Nasdaq listing fees and fees and expenses of our counsel and our accountants.

                                      -22-


                              SELLING STOCKHOLDERS

         On June 6, 2003, we entered into a securities  purchase  agreement with
certain  institutional  investors pursuant to which we issued and sold 1,052,632
shares of our common  stock at $4.75 per share and issued  warrants  to purchase
315,790  shares of our common  stock at an exercise  price of $6.91 per share to
the  investors.  Pursuant  to the above  private  placement,  we entered  into a
registration rights agreement with the institutional investors which requires us
to register on a Form S-3,  the shares  issued to the  investors  and the shares
issuable upon exercise of the warrants.

         The following table sets forth, to our knowledge,  certain  information
about the selling stockholders as of June 18, 2003.

         Beneficial  ownership is determined in accordance with the rules of the
SEC, and includes voting or investment  power with respect to shares.  Shares of
common stock  issuable  under stock  options and warrants  that are  exercisable
within 60 days after June 18,  2003 are deemed  outstanding  for  computing  the
percentage  ownership of the person holding the options and warrants but are not
deemed  outstanding for computing the percentage  ownership of any other person.
Unless  otherwise  indicated  below, to our knowledge,  all persons named in the
table have sole  voting and  investment  power with  respect to their  shares of
common  stock,  except  to the  extent  authority  is shared  by  spouses  under
applicable law. The inclusion of any shares in this table does not constitute an
admission of beneficial ownership for the person named below.


                                                                         Number of
                                                                         Shares of
                                           Shares of Common Stock      Common Stock   Shares of Common Stock to be
                                        Beneficially Owned Prior to        Being        Beneficially Owned After
    Name of Selling Stockholder                Offering (1)              Offered(1)            Offering (1)
-----------------------------------    -----------------------------   ------------   ----------------------------
                                          Number      Percentage (2)                    Number     Percentage (2)
-----------------------------------    ------------   --------------   ------------   ---------    ---------------
                                                                                           
Bonanza Master Fund Ltd.(3)........     684,211(5)        6.86%           684,211          0              *

BayStar Capital II LP(4)...........     684,211(5)        6.86%           684,211          0              *


-----------------------------------
* Less than one percent.

(1)      We do not know when or in what amounts a selling  stockholder may offer
         shares for sale. The selling  stockholders might not sell any or all of
         the shares offered by this prospectus. Because the selling stockholders
         may offer all or some of the  shares  pursuant  to this  offering,  and
         because   there  are   currently   no   agreements,   arrangements   or
         understandings with respect to the sale of any of the shares, we cannot
         estimate  the  number of the  shares  that will be held by the  selling
         stockholders after completion of the offering. However, for purposes of
         this table,  we have assumed  that,  after  completion of the offering,
         none  of the  shares  covered  by this  prospectus  will be held by the
         selling stockholders.

(2)      Applicable  percentage ownership is based on 9,818,755 shares of common
         stock outstanding as of June 18, 2003, plus any common stock equivalent
         or convertible  securities  held or shares  beneficially  owned by each
         such holder.

(3)      Mr. Bernay Box, the General  Partner of Bonanza Master Fund,  Ltd., has
         voting, dispositive and investment powers over such securities. We have
         not  previously  had  any  material   relationship  with  this  selling
         stockholder.

                                      -23-



(4)      Mr. Steven Lamar,  the Managing  Partner of BayStar  Capital II LP, has
         voting, dispositive and investment powers over such securities. We have
         not  previously  had  any  material   relationship  with  this  selling
         stockholder.

(5)      Includes  526,316  shares of  common  stock  held by each such  selling
         stockholder  and 157,895 shares of common stock issuable to the selling
         stockholders  upon  exercise  of a warrant  held by each  such  selling
         stockholder.  The exercise price to purchase each share of common stock
         pursuant to each such  warrant is $6.91 per share.  Although the shares
         of common  stock  issuable  upon  exercise of the warrants are included
         herein,  the terms of the warrants prohibit the exercise thereof in the
         event such  exercise  would  cause the  holder's  beneficial  ownership
         percentage to exceed 4.99%.

                              PLAN OF DISTRIBUTION

         The  selling  stockholders  and any of their  pledgees,  assignees  and
successors-in-interest  may, from time to time,  sell any or all of their shares
of common stock on any stock exchange,  market or trading  facility on which the
shares  are traded or in private  transactions.  These  sales may be at fixed or
negotiated  prices.  The  selling  stockholders  may  use any one or more of the
following methods when selling shares:

     -    ordinary   brokerage   transactions  and  transactions  in  which  the
          broker-dealer solicits purchasers;

     -    block  trades  in which the  broker-dealer  will  attempt  to sell the
          shares as agent but may  position and resell a portion of the block as
          principal to facilitate the transaction;

     -    purchases  by  a   broker-dealer   as  principal  and  resale  by  the
          broker-dealer for its account;

     -    an  exchange   distribution  in  accordance  with  the  rules  of  the
          applicable exchange;

     -    privately negotiated transactions;

     -    settlement of short sales;

     -    broker-dealers  may  agree  with the  selling  stockholders  to sell a
          specified number of such shares at a stipulated price per share;

     -    a combination of any such methods of sale; and

     -    any other method permitted pursuant to applicable law.

         The selling  stockholders may also sell shares under Rule 144 under the
Securities Act, if available, rather than under this prospectus.

         Broker-dealers  engaged by the  selling  stockholders  may  arrange for
other  brokers-dealers  to  participate  in sales.  Broker-dealers  may  receive
commissions or discounts from the selling stockholders (or, if any broker-dealer
acts as agent for the purchaser of shares,  from the purchaser) in amounts to be
negotiated.  The  selling  stockholders  do not  expect  these  commissions  and
discounts to exceed what is customary in the types of transactions involved.

         The  selling  stockholders  may  from  time to time  pledge  or grant a
security  interest  in some or all of the shares of common  stock  owned by them
and,  if they  default in the  performance  of their  secured  obligations,  the

                                      -24-


pledgees or secured  parties may offer and sell the shares of common  stock from
time to time under this  prospectus,  or under an amendment  to this  prospectus
under Rule  424(b)(3) or other  applicable  provision of the  Securities  Act of
1933,  as  amended,  amending  the list of selling  stockholders  to include the
pledgee,  transferee  or other  successors  in interest as selling  stockholders
under this prospectus.

         The  selling  stockholders  and any  broker-dealers  or agents that are
involved  in selling  the shares may be deemed to be  "underwriters"  within the
meaning of the Securities Act in connection with such sales. In such event,  any
commissions  received  by such  broker-dealers  or agents  and any profit on the
resale  of the  shares  purchased  by  them  may be  deemed  to be  underwriting
commissions or discounts under the Securities Act. The selling stockholders have
informed us that it does not have any  agreement or  understanding,  directly or
indirectly, with any person to distribute the common stock.

         We  are  required  to  pay  all  fees  and  expenses  incident  to  the
registration of the shares. We have agreed to indemnify the selling stockholders
against certain losses, claims,  damages and liabilities,  including liabilities
under the Securities Act.

                                  LEGAL MATTERS

         The  validity  of the shares of common  stock  offered  hereby has been
passed upon by Hale and Dorr LLP, Princeton, New Jersey.

                                     EXPERTS

         The  consolidated   financial  statements of  Cytogen  Corporation  and
subsidiaries  as of December  31,  2002 and for the year then  ended,  have been
incorporated by reference herein and in the  registration  statement in reliance
upon   the    reports    of   KPMG    LLP,    independent    accountants,    and
PricewaterhouseCoopers LLP, independent  accountants, incorporated  by reference
herein,  and upon the  authority  of said  firms as experts  in  accounting  and
auditing. The audit report covering the December 31, 2002 consolidated financial
statements  refers to KPMG LLP's audit of the  adjustments  that were applied to
restate  the 2001 and 2000  consolidated  financial  statements,  as more  fully
described in Note 1 to the consolidated financial statements.  However, KPMG LLP
was not engaged to and did not audit,  review,  or apply any  procedures  to the
2001 and 2000 consolidated  financial statements other than with respect to such
adjustments.

         The consolidated  balance sheet of  Cytogen Corporation as of  December
31, 2001 and the consolidated statements of operations, stockholders' equity and
cash flows for each of the years in the two-year period ended December 31, 2001,
have been incorporated by reference in this prospectus,  and in the registration
statement of which this  prospectus  is a part,  from the Annual  Report on Form
10-K of  Cytogen  Corporation.  The  financial  statements  for the years  ended
December 31, 2001 and  December  31, 2000 have been  audited by Arthur  Andersen
LLP,  independent public accountants,  as indicated in their report with respect
thereto,  and are incorporated by reference herein. The Company has not received
an updated or  reissued  copy of such  report  dated  February  5, 2002,  and is
relying solely upon the manually-signed report of Arthur Andersen LLP previously
provided to the Company in connection  with the Company's  Annual Report on Form
10-K for the year ended December 31, 2001. Arthur Andersen LLP has not consented
to the inclusion of their report in this prospectus,  and we have dispensed with
the requirement to file their consent in reliance on Rule 437a promulgated under
the  Securities  Act of  1933,  as  amended.  Because  Arthur  Andersen  has not
consented to the inclusion of their report in this  prospectus,  you will not be
able to recover  against Arthur  Andersen under Section 11 of the Securities Act
of 1933, as amended,  for any untrue  statements of a material fact contained in
the financial  statements audited by Arthur Andersen or any omissions to state a
material fact required to be stated therein.

                                      -25-


                       WHERE YOU CAN FIND MORE INFORMATION

         We file reports, proxy statements and other documents with the SEC. You
may read and copy any  document we file at the SEC's  public  reference  room at
Judiciary Plaza Building,  450 Fifth Street, N.W., Room 1024,  Washington,  D.C.
20549.  You  should  call  1-800-SEC-0330  for more  information  on the  public
reference  room. Our SEC filings are also available to you on the SEC's Internet
site at http://www.sec.gov.

         This prospectus is part of a registration  statement that we filed with
the  SEC.  The  registration  statement  contains  more  information  than  this
prospectus  regarding us and our common stock,  including  certain  exhibits and
schedules.  You can obtain a copy of the registration  statement from the SEC at
the address listed above or from the SEC's Internet site.

                      INFORMATION INCORPORATED BY REFERENCE

         The SEC requires us to "incorporate"  into this prospectus  information
that we file with the SEC in other  documents.  This means that we can  disclose
important  information to you by referring to other  documents that contain that
information.  The information incorporated by reference is considered to be part
of this  prospectus.  Information  contained in this  prospectus and information
that we file with the SEC in the future and  incorporate  by  reference  in this
prospectus automatically updates and supersedes previously filed information. We
incorporate  by reference the documents  listed below and any future  filings we
make with the SEC under  Sections  13(a),  13(c),  14 or 15(d) of the Securities
Exchange  Act of  1934,  prior  to the sale of all the  shares  covered  by this
prospectus.

     (1)  Our Annual  Report on Form 10-K for the year ended  December 31, 2002,
          as filed with the Securities and Exchange Commission on March 31, 2003
          (File No. 000-14879);

     (2)  Amendment  Number 1 to our Annual  Report on Form  10-K/A for the year
          ended  December 31, 2002,  as filed with the  Securities  and Exchange
          Commission on March 31, 2003 (File No. 000-14879);

     (3)  Our Current Report on Form 8-K, dated April 8, 2003, as filed with the
          Securities  and  Exchange  Commission  on  April  9,  2003  (File  No.
          000-14879);

     (4)  Our Current  Report on Form 8-K, dated May 14, 2003, as filed with the
          Securities  and  Exchange   Commission  on  May  14,  2003  (File  No.
          000-14879);

     (5)  Our Quarterly Report on Form 10-Q for the period ended March 31, 2003,
          as filed with the Securities  and Exchange  Commission on May 14, 2003
          (File No. 000-14879);

     (6)  Our Current  Report on Form 8-K, dated June 6, 2003, as filed with the
          Securities  and  Exchange   Commission  on  June  9,  2003  (File  No.
          000-14879);

     (7)  Our Current Report on Form 8-K, dated June 18, 2003, as filed with the
          Securities  and  Exchange   Commission  on  July  3,  2003  (File  No.
          000-14879);

     (8)  Our Current Report on Form 8-K, dated July 10, 2003, as filed with the
          Securities  and  Exchange  Commission  on  July  11,  2003  (File  No.
          000-14879);

     (9)  Our Current  Report on Form 8-K dated July 14, 2003, as filed with the
          Securities  and  Exchange  Commission  on  July  14,  2003  (File  No.
          000-14879);

                                      -26-

     (10) Our Current Report on Form 8-K, dated July 15, 2003, as filed with the
          Securities  and  Exchange  Commission  on  July  15,  2003  (File  No.
          000-14879);

     (11) Our Current Report on Form 8-K dated August 1, 2003, as filed with the
          Securities  and  Exchange  Commission  on  August  1,  2003  (File No.
          000-14879);

     (12) The  description  of our common stock  contained  in our  Registration
          Statement on Form 8-A, as  supplemented by the disclosure set forth in
          Exhibit 3.1 to our Form 10-Q  Quarterly  Report for the quarter  ended
          June 30, 2000 and Exhibit 3 to our Form 10-Q Quarterly  Report for the
          quarter ended June 30, 1996 (File No. 000-14879);

     (13) The description of our Series C Junior  Participating  Preferred Stock
          contained  in Exhibit 1 to our  Current  Report on Form 8-K filed with
          the  Securities  and  Exchange  Commission  on June 24, 1998 (File No.
          333-020015); and

     (14) All of our  filings  pursuant  to the  Exchange  Act after the date of
          filing the initial  registration  statement and prior to effectiveness
          of the registration statement.

         You may  request a copy of these  documents,  which will be provided to
you at no cost,  by  writing  or  telephoning  us using  the  following  contact
information:

                           Cytogen Corporation
                           650 College Road East, 3rd Floor
                           Princeton, New Jersey 08540
                           Attention:  Director, Legal
                           Telephone:  609-750-8222

         YOU SHOULD RELY ONLY ON THE  INFORMATION  INCORPORATED  BY REFERENCE OR
PROVIDED IN THIS PROSPECTUS OR ANY PROSPECTUS SUPPLEMENT. WE HAVE NOT AUTHORIZED
ANYONE  TO  PROVIDE  YOU WITH  INFORMATION  DIFFERENT  FROM  THAT  CONTAINED  OR
INCORPORATED  BY  REFERENCE IN THIS  PROSPECTUS.  THE SELLING  STOCKHOLDERS  ARE
OFFERING TO SELL, AND SEEKING OFFERS TO BUY,  SHARES OF OUR COMMON STOCK ONLY IN
JURISDICTIONS WHERE OFFERS AND SALES ARE PERMITTED. THE INFORMATION CONTAINED IN
THIS PROSPECTUS IS ACCURATE ONLY AS OF THE DATE OF THIS  PROSPECTUS,  REGARDLESS
OF THE TIME OF DELIVERY OF THIS PROSPECTUS OR OF ANY SALE OF COMMON STOCK.



                    INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Subsection (a) of Section 145 of the Delaware  General  Corporation Law
empowers a  corporation  to indemnify  any person who was or is threatened to be
made a party to any threatened, pending or completed action, suit or proceeding,
whether civil,  criminal,  administrative or investigative (other than an action
by or in the right of the  corporation)  by reason of the fact that he or she is
or was a director,  officer, employee or agent of the corporation,  or is or was
serving at the request of the  corporation as a director,  officer,  employee or
agent  of  another  corporation,  partnership,  joint  venture,  trust  or other
enterprise,  against expenses (including attorneys' fees), judgments,  fines and
amounts paid in  settlement  actually and  reasonably  incurred by him or her in
connection with such action, suit or proceeding if he or she acted in good faith
and in a manner he or she  reasonably  believed  to be in or not  opposed to the
best interests of the  corporation,  and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.

                                      -27-

         Subsection  (b) of Section 145 empowers a corporation  to indemnify any
person  who  was or is a  party  or is  threatened  to be  made a  party  to any
threatened,  pending  or  completed  action  or suit by or in the  right  of the
corporation  to procure a judgment in its favor by reason of the fact that he or
she is or was a director,  officer, employee or agent of the corporation,  or is
or was  serving  at the  request  of the  corporation  as a  director,  officer,
employee or agent of another corporation,  partnership,  joint venture, trust or
other  enterprise,  against  expenses  (including  attorneys' fees) actually and
reasonably  incurred by him or her in connection  with the defense or settlement
of such  action or suit if he or she  acted in good  faith and in a manner he or
she  reasonably  believed to be in or not opposed to the best  interests  of the
corporation and except that no  indemnification  shall be made in respect of any
claim,  issue or matter as to which such person  shall have been  adjudged to be
liable  to the  corporation  unless  and only to the  extent  that the  Court of
Chancery or the court in which such action or suit was brought  shall  determine
upon application that,  despite the adjudication of liability but in view of all
of the circumstances of the case, such person is fairly and reasonably  entitled
to indemnity for such  expenses  which the Court of Chancery or such other court
shall deem proper.

         Section 145 further  provides  that to the extent a director or officer
of a  corporation  has been  successful  in the defense of any  action,  suit or
proceeding referred to in subsection (a) and (b) or in the defense of any claim,
issue or  matter  therein,  he or she  shall  be  indemnified  against  expenses
(including  attorneys'  fees) actually and reasonably  incurred by him or her in
connection therewith; that the indemnification provided by Section 145 shall not
be deemed  exclusive of any other rights to which the  indemnified  party may be
entitled; and that the scope of indemnification extends to directors,  officers,
employees, or agents of a constituent corporation absorbed in a consolidation or
merger and persons  serving in that  capacity at the request of the  constituent
corporation for another. Section 145 also empowers a corporation to purchase and
maintain insurance on behalf of a director or officer of the corporation against
any liability  asserted against him or her or incurred by him or her in any such
capacity  or  arising  out of his or her  status  as  such  whether  or not  the
corporation  would  have  the  power  to  indemnify  him  or  her  against  such
liabilities under Section 145.

         Section  102(b)(7) of the Delaware  General  Corporation  Law enables a
corporation in its certificate of incorporation to limit the personal  liability
of members of its board of directors  for  violation  of a director's  fiduciary
duty of care. This section does not, however,  limit the liability of a director
for breaching his or her duty of loyalty, failing to act in good faith, engaging
in intentional misconduct or knowingly violating a law, authorizing a payment of
a dividend or approving a stock  repurchase  in violation of Delaware  Corporate
Law or from any transaction in which the director  derived an improper  personal
benefit.  This  section  also will have no  effect on claims  arising  under the
federal securities laws.

         The Company's Certificate of Incorporation and By-Laws provide that the
Company shall indemnify  officers and directors and, to the extent  permitted by
the Board of Directors,  employees and agents of the Company, to the full extent
permitted  by and in the  manner  permissible  under  the  laws of the  State of
Delaware.  In addition,  the By-Laws  permit the Board of Directors to authorize
the Company to purchase and maintain  insurance  against any director,  officer,
employee or agent of the Company arising out of his capacity as such.

         Cytogen  has  obtained  liability  insurance  for  the  benefit  of its
directors  and officers  which  provides  coverage  for losses of directors  and
officers for  liabilities  arising out of claims  against such persons acting as
directors or officers of Cytogen (or any  subsidiary  thereof) due to any breach
of duty, neglect,  error,  misstatement,  misleading statement,  omission or act
done by such directors and officers, except as prohibited by law.

                                      -28-



                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14.      OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

         The following  table sets forth the various  expenses to be incurred in
connection  with the sale and  distribution of the securities  being  registered
hereby,  all  of  which  will  be  borne  by  Cytogen  Corporation  (except  any
underwriting  discounts  and  commissions  and expenses  incurred by the selling
stockholders  for  brokerage,  accounting,  tax or legal  services  or any other
expenses incurred by the selling  stockholders in disposing of the shares).  All
amounts  shown are  estimates  except the  Securities  and  Exchange  Commission
registration fee.

    Filing Fee - Securities and Exchange Commission ..........       $ 822.54

    Legal fees and expenses...................................     $30,000.00

    Accounting fees and expenses..............................     $12,000.00
                                                                   ----------

             Total Expenses...................................     $42,822.54

ITEM 15.      INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         Subsection (a) of Section 145 of the Delaware  General  Corporation Law
empowers a  corporation  to indemnify  any person who was or is threatened to be
made a party to any threatened, pending or completed action, suit or proceeding,
whether civil,  criminal,  administrative or investigative (other than an action
by or in the right of the  corporation)  by reason of the fact that he or she is
or was a director,  officer, employee or agent of the corporation,  or is or was
serving at the request of the  corporation as a director,  officer,  employee or
agent  of  another  corporation,  partnership,  joint  venture,  trust  or other
enterprise,  against expenses (including attorneys' fees), judgments,  fines and
amounts paid in  settlement  actually and  reasonably  incurred by him or her in
connection with such action, suit or proceeding if he or she acted in good faith
and in a manner he or she  reasonably  believed  to be in or not  opposed to the
best interests of the  corporation,  and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.

         Subsection  (b) of Section 145 empowers a corporation  to indemnify any
person  who  was or is a  party  or is  threatened  to be  made a  party  to any
threatened,  pending  or  completed  action  or suit by or in the  right  of the
corporation  to procure a judgment in its favor by reason of the fact that he or
she is or was a director,  officer, employee or agent of the corporation,  or is
or was  serving  at the  request  of the  corporation  as a  director,  officer,
employee or agent of another corporation,  partnership,  joint venture, trust or
other  enterprise,  against  expenses  (including  attorneys' fees) actually and
reasonably  incurred by him or her in connection  with the defense or settlement
of such  action or suit if he or she  acted in good  faith and in a manner he or
she  reasonably  believed to be in or not opposed to the best  interests  of the
corporation and except that no  indemnification  shall be made in respect of any
claim,  issue or matter as to which such person  shall have been  adjudged to be
liable  to the  corporation  unless  and only to the  extent  that the  Court of
Chancery or the court in which such action or suit was brought  shall  determine
upon application that,  despite the adjudication of liability but in view of all
of the circumstances of the case, such person is fairly and reasonably  entitled
to indemnity for such  expenses  which the Court of Chancery or such other court
shall deem proper.

                                      II-1


         Section 145 further  provides  that to the extent a director or officer
of a  corporation  has been  successful  in the defense of any  action,  suit or
proceeding referred to in subsection (a) and (b) or in the defense of any claim,
issue or  matter  therein,  he or she  shall  be  indemnified  against  expenses
(including  attorneys'  fees) actually and reasonably  incurred by him or her in
connection therewith; that the indemnification provided by Section 145 shall not
be deemed  exclusive of any other rights to which the  indemnified  party may be
entitled; and that the scope of indemnification extends to directors,  officers,
employees, or agents of a constituent corporation absorbed in a consolidation or
merger and persons  serving in that  capacity at the request of the  constituent
corporation for another. Section 145 also empowers a corporation to purchase and
maintain insurance on behalf of a director or officer of the corporation against
any liability  asserted against him or her or incurred by him or her in any such
capacity  or  arising  out of his or her  status  as  such  whether  or not  the
corporation  would  have  the  power  to  indemnify  him  or  her  against  such
liabilities under Section 145.

         Section  102(b)(7) of the Delaware  General  Corporation  Law enables a
corporation in its certificate of incorporation to limit the personal  liability
of members of its board of directors  for  violation  of a director's  fiduciary
duty of care. This section does not, however,  limit the liability of a director
for breaching his or her duty of loyalty, failing to act in good faith, engaging
in intentional misconduct or knowingly violating a law, authorizing a payment of
a dividend or approving a stock  repurchase  in violation of Delaware  Corporate
Law or from any transaction in which the director  derived an improper  personal
benefit.  This  section  also will have no  effect on claims  arising  under the
federal securities laws.

         The Company's Certificate of Incorporation and By-Laws provide that the
Company shall indemnify  officers and directors and, to the extent  permitted by
the Board of Directors,  employees and agents of the Company, to the full extent
permitted  by and in the  manner  permissible  under  the  laws of the  State of
Delaware.  In addition,  the By-Laws  permit the Board of Directors to authorize
the Company to purchase and maintain  insurance  against any director,  officer,
employee or agent of the Company arising out of his capacity as such.

         Cytogen  has  obtained  liability  insurance  for  the  benefit  of its
directors  and officers  which  provides  coverage  for losses of directors  and
officers for  liabilities  arising out of claims  against such persons acting as
directors or officers of Cytogen (or any  subsidiary  thereof) due to any breach
of duty, neglect,  error,  misstatement,  misleading statement,  omission or act
done by such directors and officers, except as prohibited by law.

ITEM 16.      EXHIBITS AND FINANCIAL SCHEDULES.

         (a)     Exhibits

                  5.1*   Opinion of Hale and Dorr LLP.

                  10.1   Securities   Purchase  Agreement  by  and  among  the
                         Company  and  the  Purchasers  dated  July  10,  2003
                         (incorporated  by reference to the Company's  Current
                         Report on Form 8-K,  filed  with the  Securities  and
                         Exchange  Commission  on July 11,  2003)  (Commission
                         File No. 000-14879).

                  10.2   Form of Common Stock  Purchase  Warrant issued by the
                         Company  in favor of each  Purchaser  dated  July 10,
                         2003  (incorporated  by  reference  to the  Company's
                         Current Report on Form 8-K, filed with the Securities
                         and Exchange Commission on July 11, 2003) (Commission
                         File No. 000-14879).

                                      II-2


                  10.3   Registration   Rights  Agreement  by  and  among  the
                         Company  and  the  Purchasers  dated  July  10,  2003
                         (incorporated  by reference to the Company's  Current
                         Report on Form 8-K,  filed  with the  Securities  and
                         Exchange  Commission  on July 11,  2003)  (Commission
                         File No. 000-14879).

                  23.1*  Consent of KPMG LLP.

                  23.2*  Consent of PricewaterhouseCoopers LLP.

                  23.3*  Consent of Hale and Dorr LLP (Included in Exhibit 5.1).

                  24.1*  Power of Attorney (Included on signature page).

----------
*     Filed herewith.


ITEM 17.      UNDERTAKINGS.

         The undersigned Registrant hereby undertakes:

     (1) To file,  during any period in which  offers or sales are being made, a
post-effective amendment to this Registration Statement:

     (i)  To  include  any  prospectus  required  by  Section  10(a)(3)  of  the
          Securities Act of 1933, as amended (the "Securities Act");

     (ii) To reflect in the  prospectus  any facts or events  arising  after the
          effective  date of this  Registration  Statement  (or the most  recent
          post-effective  amendment  thereof)  which,  individually  or  in  the
          aggregate, represent a fundamental change in the information set forth
          in this Registration  Statement.  Notwithstanding  the foregoing,  any
          increase  or decrease  in volume of  securities  offered (if the total
          dollar  value of  securities  offered  would not exceed that which was
          registered)  and  any  deviation  from  the  low  or  high  end of the
          estimated  maximum  offering  range  may be  reflected  in the form of
          prospectus  filed with the  Commission  pursuant to Rule 424(b) if, in
          the aggregate,  the changes in volume and price represent no more than
          20% change in the maximum  aggregate  offering  price set forth in the
          "Calculation of Registration Fee" table in the effective  Registration
          Statement; and

     (iii)To  include  any  material  information  with  respect  to the plan of
          distribution not previously  disclosed in this Registration  Statement
          or any  material  change  to such  information  in  this  Registration
          Statement;

provided,  however,  that  paragraphs  (1)(i)  and  (1)(ii)  do not apply if the
information  required  to be  included in a  post-effective  amendment  by those
paragraphs  is  contained  in periodic  reports  filed with or  furnished to the
Commission  by the  Registrant  pursuant  to Section 13 or Section  15(d) of the
Securities  Exchange Act of 1934,  as amended  (the  "Exchange  Act"),  that are
incorporated by reference in this Registration Statement.

     (2)  That,  for  the  purposes  of  determining  any  liability  under  the
Securities  Act,  each  post-effective  amendment  shall be  deemed  to be a new

                                      II-3

registration  statement  relating to the  securities  offered  therein,  and the
offering of such  securities  at the time shall be deemed to be the initial bona
fide offering thereof.

     (3) To remove from registration by means of a post-effective  amendment any
of the securities being registered which remain unsold at the termination of the
offering.

         The Registrant  hereby undertakes that, for purposes of determining any
liability  under the  Securities  Act,  each filing of the  Registrant's  annual
report  pursuant  to  Section  13(a) or 15(d) of the  Exchange  Act (and,  where
applicable,  each filing of an employee benefit plan's annual report pursuant to
Section  15(d) of the Exchange  Act) that is  incorporated  by reference in this
Registration  Statement  shall  be  deemed  to be a new  registration  statement
relating to the securities offered therein,  and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

         Insofar as indemnification for liabilities arising under the Securities
Act may be  permitted to  directors,  officers  and  controlling  persons of the
Registrant  pursuant to the  indemnification  provisions  described  herein,  or
otherwise, the Registrant has been advised that in the opinion of the Securities
and  Exchange  Commission  such  indemnification  is  against  public  policy as
expressed in the Securities Act and is, therefore,  unenforceable.  In the event
that a claim  for  indemnification  against  such  liabilities  (other  than the
payment by the Registrant of expenses incurred or paid by a director, officer or
controlling  person of the Registrant in the  successful  defense of any action,
suit or proceeding) is asserted by such director,  officer or controlling person
in connection with the securities being registered,  the Registrant will, unless
in the  opinion  of its  counsel  the matter  has been  settled  by  controlling
precedent,  submit to a court of appropriate  jurisdiction  the question whether
such  indemnification  by it is  against  public  policy  as  expressed  in  the
Securities Act and will be governed by the final adjudication of such issue.

                                      II-4


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the  requirements  for  filing  on  Form  S-3 and has  duly  caused  this
Amendment  to the  Registration  Statement  to be  signed  on its  behalf by the
undersigned,  thereunto duly authorized, in the City of Princeton,  State of New
Jersey, on August 12, 2003.

                                CYTOGEN CORPORATION


                                By:   /s/ Michael D. Becker
                                      -------------------------------------
                                      Michael D. Becker
                                      President and Chief Executive Officer







                        SIGNATURES AND POWER OF ATTORNEY

         Pursuant to the requirements of the Securities Act of 1933, as amended,
this  Amendment to the  Registration  Statement has been signed by the following
persons in the capacities and on the dates indicated.



               SIGNATURE                                 TITLE                           DATE
------------------------------------     --------------------------------------     ---------------
                                                                              
/s/ Michael D. Becker                    President, Chief Executive Officer and     August 12, 2003
------------------------------------     Director (Principal Executive Officer)
Michael D. Becker

/s/ Thu A. Dang                          Vice President, Finance (Principal         August 12, 2003
------------------------------------     Financial and Accounting Officer)
Thu A. Dang

                    *                    Director                                   August 12, 2003
------------------------------------
John E.  Bagalay, Jr.

                    *                    Director                                   August 12, 2003
------------------------------------
Allen Bloom

                    *                    Director                                   August 12, 2003
------------------------------------
Stephen K.  Carter

                    *                    Director                                   August 12, 2003
------------------------------------
James A. Grigsby

                    *                    Director                                   August 12, 2003
-----------------------------------
Robert F.  Hendrickson

                    *                    Director                                   August 12, 2003
-----------------------------------
Kevin G. Lokay

                    *                    Director                                   August 12, 2003
-----------------------------------
H. Joseph Reiser



*   By the  signature  set forth  below,  the  undersigned, pursuant to the duly
authorized powers of attorney filed with the Securities and Exchange  Commission
has signed this Amendment to the Registration  Statement on behalf of the person
indicated.

/s/Michael D. Becker
--------------------
Michael D. Becker
(Attorney-in-Fact)






                                  EXHIBIT INDEX


  EXHIBIT NUMBER                            DESCRIPTION
  --------------    ------------------------------------------------------------
       5.1*         Opinion of Hale and Dorr LLP.

       10.1         Securities  Purchase  Agreement by and among the Company and
                    the  Purchasers   dated  July  10,  2003   (incorporated  by
                    reference to the Company's Current Report on Form 8-K, filed
                    with the  Securities  and  Exchange  Commission  on July 11,
                    2003) (Commission File No. 000-14879).

       10.2         Form of Common Stock Purchase  Warrant issued by the Company
                    in favor of each Purchaser dated July 10, 2003 (incorporated
                    by reference to the  Company's  Current  Report on Form 8-K,
                    filed with the  Securities  and Exchange  Commission on July
                    11, 2003) (Commission File No. 000-14879).

       10.3         Registration  Rights  Agreement by and among the Company and
                    the  Purchasers   dated  July  10,  2003   (incorporated  by
                    reference to the Company's Current Report on Form 8-K, filed
                    with the  Securities  and  Exchange  Commission  on July 11,
                    2003) (Commission File No. 000-14879).

      23.1*         Consent of KPMG LLP.

      23.2*         Consent of PricewaterhouseCoopers LLP.

      23.3*         Consent of Hale and Dorr LLP (Included in Exhibit 5.1).

      24.1*         Power of Attorney (Included on signature page).

----------
*  Filed herewith.