EXHIBIT 99.1

Shire Pharmaceuticals Group plc
Hampshire International Business Park,
Chineham, Basingstoke RG24 8EP UK
Tel +44 1256 894000 Fax +44 1256 894708
http://www.shire.com

Barr lawsuit update

Basingstoke, UK – 17^th December 2003 – Shire Pharmaceuticals Group plc (LSE: SHP, NASDAQ: SHPGY, TSX: SHQ) announces that the lawsuits filed against Barr Laboratories Inc. (‘Barr’) for infringement of Shire Laboratories’ US 6,322,819 (‘819) and 6,605,300 (‘300) patents have been consolidated and that the trial date has been moved from July 2005 to January 2006.

The lawsuits result from the ANDA (Abbreviated New Drug Application) filed by Barr for a generic version of ADDERALL XR®, pursuant to which Barr provided notice that it would seek to market its generic product before expiration of the ‘819 and ‘300 patents in 2018.

ADDERALL XR is the lead product in Shire’s portfolio of treatment for Attention Deficit and Hyperactivity Disorder (ADHD).

Ends

For further information please contact:

Investor Relations
Gordon Ngan	+44 1256 894 160
Media
Jessica Mann	+44 1256 894 280

Notes to editors

Shire Pharmaceuticals Group plc

Shire Pharmaceuticals Group plc (Shire) is a global specialty pharmaceutical company with a strategic focus on meeting the needs of the specialist physician and currently focuses on developing projects and marketing products in the areas of central nervous system (CNS), gastrointestinal (GI), and renal diseases. Shire has operations in the world’s key pharmaceutical markets (US, Canada, UK, France, Italy, Spain and Germany) as well as a specialist drug delivery unit in the US.

For further information on Shire, please visit the Company’s website: www.shire.com

THE “SAFE HARBOR” STATEMENT UNDER THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995

Statements included herein that are not historical facts, are forward-looking statements. Such forward-looking statements involve a number of risks and uncertainties and are subject to change at any time. In the event such risks or uncertainties materialize, Shire’s results could be materially affected. The risks and uncertainties include, but are not limited to, risks associated with the inherent uncertainty of pharmaceutical

research, product development, manufacturing and commercialization, the impact of competitive products, including, but not limited to, the impact on Shire’s Attention Deficit Hyperactivity Disorder (ADHD) franchise, patents, including but not limited to, legal challenges relating to Shire’s ADHD franchise, government regulation and approval, including but not limited to the expected product approval date of lanthanum carbonate (FOSRENOL®), METHYPATCH®, XAGRID® and the adult indication for ADDERALL XR® and other risks and uncertainties detailed from time to time in our filings, including the Annual Report filed on Form 10-K by Shire with the Securities and Exchange Commission.