Total Voting Rights

GW Pharmaceuticals PLC ("GW Pharmaceuticals"): Total voting rights

Porton Down, UK, 31 March 2010: GW Pharmaceuticals (AIM: GWP) hereby provides notification of the following information for the purposes of Rule 5.6.1R of the Disclosure and Transparency Rules:

GW Pharmaceuticals' issued share capital consists of 129,843,322 ordinary shares of 0.1p each with voting rights. There are no shares held in treasury. Therefore, the total number of voting rights in GW is 129,843,322.

The above figure may be used by shareholders as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, GW Pharmaceuticals under the FSA's Disclosure and Transparency Rules.

For further information, please contact:

GW Pharmaceuticals PLC +44 (0)1980 557 000

Adam George, Company Secretary

Piper Jaffray Ltd (Nominated Adviser)

Neil Mackison/Rupert Winckler +44 (0) 203 142 8700

Notes to Editors:

About GW Pharmaceuticals

GW Pharmaceuticals was founded in 1998 and listed on the AIM, a market of the London Stock Exchange, in June 2001. Operating under license from the UK Home Office, the company researches and develops cannabinoid pharmaceutical products for patients who suffer from a range of serious ailments, in particular multiple sclerosis and cancer pain. GW has assembled a large in-house scientific team with expertise in cannabinoid science as well as experience in the development of both plant-based prescription pharmaceutical products and medicines containing controlled substances. GW occupies a world leading position in cannabinoids and has developed an extensive international network of the most prominent scientists in the field. For more information, visit www.gwpharm.com