File No. 333-110040
                                                      Filed under Rule 424(b)(3)


               PROSPECTUS SUPPLEMENT NO. 1 DATED NOVEMBER 6, 2003

                    To the Prospectus dated October 28, 2003

                               CYTOGEN CORPORATION

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         This   prospectus   supplement   supplements  and  should  be  read  in
conjunction with the prospectus dated October 28, 2003,  relating to $60,000,000
in shares of our common  stock that we may offer and sell from time to time.  We
will receive all of the proceeds from any shares sold.  The prospectus was filed
as part of our registration statement on Form S-3 (No. 333-110040).

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

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

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         No dealer,  salesperson or any other person has been authorized to give
any  information or make any  representations  not contained in this  prospectus
supplement  or the  prospectus  and,  if  given  or  made,  the  information  or
representations  must not be relied upon as having been  authorized  by us. This
prospectus  supplement and the prospectus do not constitute an offer to sell, or
a  solicitation  of an  offer  to  buy,  any  securities  to any  person  in any
jurisdiction where such an offer or solicitation would be unlawful.  Neither the
delivery  of this  prospectus  supplement  or the  prospectus  nor any sale made
hereunder or thereunder shall,  under any  circumstance,  create any implication
that the  information  contained  herein or  therein  is  correct as of any time
subsequent to the date hereof.

Stock Purchase

         On November 6, 2003, we entered into a share purchase agreement for the
sale of an  aggregate  of  1,863,637  shares  of our  common  stock  to  certain
institutional  investors for an aggregate  purchase  price of  $20,500,000.  The
prospectus  provides for the sale of up to $60,000,000  in registered  shares of
our common stock.

                                November 6, 2003