Product Update

GW Pharmaceuticals plc

("GW" or "the Group")

Product Update

Porton Down, UK, 18 June 2010: Consistent with previous guidance that a UK approval for Sativex is expected by the end of Q2 2010, GW confirms that it has just received formal notification of the grant of a product licence from MHRA for Sativex. GW's marketing partner, Bayer Schering Pharma, will be announcing the formal UK launch of Sativex on Monday 21 June and further details will be provided at that time.

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About GW

GW 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.

This news release may contain forward-looking statements that reflect GWs current expectations regarding future events, including development and regulatory clearance of the GW's products. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors, including (inter alia), the success of the GW's research strategies, the applicability of the discoveries made therein, the successful and timely completion of uncertainties related to the regulatory process, and the acceptance of Sativex® and other products by consumer and medical professionals.