Notice of Results

GW Pharmaceuticals to Report Q3 2013 Results and

Host Conference Call on 5 August, 2013

London, UK, 15 July 2013: GW Pharmaceuticals plc (Nasdaq: GWPH, AIM: GWP, "GW" or "the Company"), a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics from its proprietary cannabinoid product platform, will announce on 5 August 2013 its financial results for the third quarter ending 30 June, 2013. GW will also host a conference call the same day at 1:00 p.m. BST (8:00 a.m. EST).

Conference call information will be provided in the financial results press release. A replay of the call will also be available through the Company's website (www.gwpharm.com) shortly after the call.

About GW Pharmaceuticals plc

Founded in 1998, GW is a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics from its proprietary cannabinoid product platform in a broad range of disease areas. GW commercialized the world's first plant-derived cannabinoid prescription drug, Sativex®, which is approved for the treatment of spasticity due to multiple sclerosis in 21 countries. Sativex is also in Phase 3 clinical development as a potential treatment of pain in people with advanced cancer. This Phase 3 program is intended to support the submission of a New Drug Application for Sativex in cancer pain with the U.S. Food and Drug Administration and in other markets around the world. GW has established a world leading position in the development of plant-derived cannabinoid therapeutics and has a deep pipeline of additional cannabinoid product candidates, including two distinct compounds, GWP42004 and GWP42003, in Phase 2 clinical development for Type 2 diabetes and ulcerative colitis, respectively, and at least two additional programs expected to enter Phase 1 and Phase 2 clinical trials in the next 12 months. For further information, please visit www.gwpharm.com.

Enquiries:

GW Pharmaceuticals plc

Justin Gover, CEO

+44 1980 557000

Stephen Schultz, VP Investor Relations

+ 1 401 500 6570

FTI Consulting

Ben Atwell / Simon Conway / John Dineen (European media enquiries)

 +44 20 7831 3113

Robert Stanislaro (US media enquiries)

+1 212 850 5657

Trout Group, LLC (US investor relations)

Seth Lewis / Todd James

 +1 646 378 2900

Peel Hunt LLP (UK Nominated Adviser and Broker)

James Steel / Vijay Barathan

 +44 20 7418 8900