FORM 6-K



                       SECURITIES AND EXCHANGE COMMISSION
                              Washington D.C. 20549



                            Report of Foreign Issuer



                      Pursuant to Rule 13a-16 or 15d-16 of
                       the Securities Exchange Act of 1934


                       For period ending March 12, 2008

                               GlaxoSmithKline plc
                              (Name of registrant)



               980 Great West Road, Brentford, Middlesex, TW8 9GS
                    (Address of principal executive offices)


             Indicate by check mark whether the registrant files or
                 will file annual reports under cover Form 20-F
                                  or Form 40-F


                              Form 20-F x Form 40-F
                                       --


         Indicate by check mark whether the registrant by furnishing the
        information contained in this Form is also thereby furnishing the
       information to the Commission pursuant to Rule 12g3-2(b) under the
                        Securities Exchange Act of 1934.

                                    Yes No x
                                       --


   Notification of Transactions of Directors, Persons Discharging Managerial
                      Responsibility or Connected Persons

I give below details of changes in the interests of Directors, Persons
Discharging Managerial Responsibility or Connected Persons in the Ordinary
shares of GlaxoSmithKline plc in respect of the under-mentioned persons arising
from the purchase of Ordinary shares at a price of GBP10.37 per Ordinary share
on 11 March 2008 through the Company's ShareReward Plan ("the Plan") which the
under mentioned persons entered on 5 October 2001:


Mr J S Heslop           Acquisition of 12 Ordinary shares under the partnership
                        element of the Plan (personal contribution)

                        Acquisition of 12 Ordinary shares under the matching
                        element of the Plan (Company contribution)


Mr R M Bondy            Acquisition of 12 Ordinary shares under the partnership
                        element of the Plan (personal contribution)

                        Acquisition of 12 Ordinary shares under the matching
                        element of the Plan (Company contribution)


Mr E J Gray             Acquisition of 12 Ordinary shares under the partnership
                        element of the Plan (personal contribution)

                        Acquisition of 12 Ordinary shares under the matching
                        element of the Plan (Company contribution)


Mr D Learmouth          Acquisition of 12 Ordinary shares under the partnership
                        element of the Plan (personal contribution)

                        Acquisition of 12 Ordinary shares under the matching
                        element of the Plan (Company contribution)


Mr A P Witty            Acquisition of 12 Ordinary shares under the partnership
                        element of the Plan (personal contribution)

                        Acquisition of 12 Ordinary shares under the matching
                        element of the Plan (Company contribution)

The Company and the above-mentioned persons were advised of this information on
12 March 2008.

This notification relates to a transaction notified in accordance with
Disclosure and Transparency Rule 3.1.4R(1)(a).


S M Bicknell
Company Secretary


12 March 2008




SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorised.



                                                             GlaxoSmithKline plc
                                                                    (Registrant)

Date: March 12, 2008                                          By: VICTORIA WHYTE
                                                              ------------------
                                                              Victoria Whyte
                                                 Authorised Signatory for and on
                                                   behalf of GlaxoSmithKline plc