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 May 06, 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 GlaxoSmithKline Performance Share Plan notified the Company and the under-mentioned persons on 6 May 2008 of an increase in their notional interests in Ordinary shares at a price of GBP11.20 per share and Ordinary Share ADRs at a price of $44.11 per ADR following the notional re-investment of the dividend to be paid to shareholders on 10 July 2008. Ordinary shares ADRs Dr JP Garnier 5,730.80 Mr A P Witty 4,604.87 Mr J S Heslop 3,742.11 Dr M M Slaoui 332.90 1,657.54 Mrs C E Bruck Slaoui 26.53 37.72 Mr C Viehbacher 1,508.67 Mr J M Clarke 2,790.11 Mr M Dunoyer 1,050.82 Mr E J Gray 870.97 Dr R G Greig 917.26 Mr D Learmouth 573.76 Mr W C Louv 666.68 Mr D J Phelan 1,412.58 Dr D Pulman 917.26 Mr S M Werner 191.52 The notional dividends accrued will be paid out in proportion to the percentage of participants' Performance Share Plan holdings that vest following the end of the relevant three year measurement period. This notification relates to transactions notified in accordance with Disclosure and Transparency Rules 3.1.4R(1)(a). S M Bicknell Company Secretary 6 May 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: May 06, 2008 By: VICTORIA WHYTE ------------------ Victoria Whyte Authorised Signatory for and on behalf of GlaxoSmithKline plc