Press Release

Cambridge, MA, July 19, 2005 - Vertex Pharmaceuticals Incorporated (Nasdaq: VRTX) today announced that its collaborator, GlaxoSmithKline (GSK), has received fast track designation for the HIV protease inhibitor (PI) 640385 (VX-385) from the United States Food and Drug Administration. GSK plans to initiate a Phase IIb study of 640385 in HIV-infected patients in the third quarter of 2005. 640385 is the third, orally active HIV protease inhibitor to be developed as part of the collaboration agreement between Vertex and GSK.

"The Food and Drug Administration's fast track designation for 640385 highlights the productive collaboration between Vertex and GlaxoSmithKline, which has generated three novel HIV protease inhibitor product candidates over the past 12 years, and has established both companies as leaders in the development of new drugs to treat HIV infection," said Joshua Boger, Ph.D., Chairman, President and CEO of Vertex. "This designation recognizes the clinical and nonclinical results for 640385, which support the potential to address the needs of patients with resistant HIV strains."

Under the FDA Modernization Act of 1997, fast track designation indicates that the FDA will facilitate the development and may expedite the review of a drug if it is intended for the treatment of a serious or life-threatening condition, and demonstrates the potential to address an unmet medical need for such a condition. Support of this fast track designation was based on positive Phase IIa data from a clinical study of 640385 in HIV-infected patients, as well as results from in vitro studies indicating 640385's antiviral activity against HIV-1 strains resistant to a number of currently marketed protease inhibitors. Vertex expects that GSK will present preliminary Phase IIa results at a medical conference in the second half of 2005.

About Vertex

Vertex Pharmaceuticals Incorporated is a global biotechnology company committed to the discovery and development of breakthrough small molecule drugs for serious diseases. The Company's strategy is to commercialize its products both independently and in collaboration with major pharmaceutical companies. Vertex's product pipeline is principally focused on viral diseases, inflammation, autoimmune diseases and cancer. In collaboration with GlaxoSmithKline, Vertex currently co-promotes the protease inhibitor Lexiva®.

Safe Harbor Statement

This press release may contain forward-looking statements, including statements that (i) GSK plans to initiate a Phase IIb study of 640385 (VX-385) in HIV-infected patients in the third quarter of 2005; (ii) the Food and Drug Administration's fast track designation for 640385 recognizes the clinical and nonclinical results for 640385, which support the potential to address the needs of patients with resistant HIV strains; (iii) Vertex expects that GSK will present preliminary Phase IIa results at a medical conference in the second half of 2005. While management makes its best efforts to be accurate in making forward-looking statements, such statements are subject to risks and uncertainties that could cause Vertex's actual results to vary materially. These risks and uncertainties include, among other things, the risks that clinical trials for 640385 may not proceed as planned due to technical, scientific, supply or patient enrollment issues, that actual clinical studies of 640385 will not reflect the results obtained in earlier clinical and nonclinical testing and other risks listed under Risk Factors in Vertex's Form 10-K filed with the Securities and Exchange Commission on March 16, 2005.

Lexiva® is a registered trademark of the GlaxoSmithKline group of companies.

Vertex Contacts:
Lynne H. Brum, VP, Corporate Communications and Financial Planning, (617) 444-6614
Michael Partridge, Director, Corporate Communications, (617) 444-6108
Lora Pike, Manager, Investor Relations, (617) 444-6755
Zachry Barber, Specialist, Media Relations, (617) 444-6470