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 April 17, 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





The  Administrators  of the Deferred  Investment Award Plan notified the Company
and Mr Gray on 17 April 2008 of an increase in his interests in Ordinary  shares
at a price of GBP11.05 per share  following  the  re-investment  of the dividend
paid to shareholders on 10 April 2008.




Mr E J Gray          312.41



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





S M Bicknell
Company Secretary



17 April 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: April 17, 2008                                      By: VICTORIA WHYTE
                                                              ------------------
                                                              Victoria Whyte
                                                 Authorised Signatory for and on
                                                   behalf of GlaxoSmithKline plc