U.S. Patent Office Confirms First of Four Viread®Patents

Gilead Sciences, Inc. (Nasdaq:GILD) today announced that the U.S. Patent

& Trademark Office (PTO) has completed the first of four reexamination

proceedings and has confirmed the patentability of U.S. Patent No.

6,043,230, which covers a method of use for Viread (tenofovir disoproxil

fumarate). The U.S. PTO has not announced its ruling on the remaining

three Viread patents under review. The four U.S. PTO review proceedings were initiated July 2007 in

response to a challenge issued by the Public Patent Foundation (PUBPAT)

in March 2007 for U.S. Patents No. 5,922,695; 5,977,089; 5,935,946; and

6,043,230. In its request for the reexaminations, PUBPAT claimed that

prior art existed that would have impacted the issuance of the original

patents. Upon completion of the first reexamination proceeding, the U.S. PTO has

confirmed the patentability of U.S. Patent No. 6,043,230 with no

reduction in the scope of the claims. "We are pleased that the U.S. PTO, following a

detailed and comprehensive analysis, has concluded this first

reexamination," said Gregg Alton, Senior Vice

President and General Counsel. "We have always

believed that the U.S. PTO would recognize that Viread is a novel

product, and we remain confident that the office will rule similarly on

the remaining three patents under review." About Gilead Sciences Gilead Sciences is a biopharmaceutical company that discovers, develops

and commercializes innovative therapeutics in areas of unmet medical

need. The company´s mission is to advance the

care of patients suffering from life-threatening diseases worldwide.

Headquartered in Foster City, California, Gilead has operations in North

America, Europe and Australia. Forward-Looking Statement This press release includes forward-looking statements, within the

meaning of the Private Securities Litigation Reform Act of 1995, that

are subject to risks, uncertainties and other factors, including

uncertainty related to the expected timing of the U.S. PTO´s

ruling on the remaining three Viread patents, the risk that the U.S. PTO

may narrow or invalidate some or all of the original claims in such

patents and the risk of the ultimate enforceability of this patent

should it be challenged in a court of law. These risks, uncertainties

and other factors could cause actual results to differ materially from

those referred to in the forward-looking statements. The reader is

cautioned not to rely on these forward-looking statements. These and

other risks are described in detail in Gilead´s Annual Report on Form

10-K for the year ended December 31, 2007 and Quarterly Report on Form

10-Q for the quarter ended March 31, 2008, as filed with the U.S.

Securities and Exchange Commission. All forward-looking statements are

based on information currently available to Gilead, and Gilead assumes

no obligation to update any such forward-looking statements. Viread is a registered trademark of Gilead Sciences, Inc. For more information on Gilead, please call the Gilead Public Affairs

Department at 1-800-GILEAD-5 (1-800-445-3235) or visit www.gilead.com