Gilead and Roche End Tamiflu(R) Dispute; Expanded Collaboration Includes Gilead Role in Oversight of Manufacturing and Commercialization

Tamiflu, the only oral antiviral for the treatment and preventionof influenza A and B, was invented by Gilead and licensed to Roche in1996. The companies collaborated on the development of the product,advancing Tamiflu through clinical trials, initiated in 1997, to itsfirst market approval approximately two and a half years later. InJune of this year, Gilead delivered a notice of termination to Rochefor the companies' 1996 Agreement and the companies subsequentlyentered into arbitration. With today's execution of an amendment tothe 1996 agreement, Gilead has terminated arbitration proceedings withRoche.

Under the terms of the amended agreement, Gilead and Roche willestablish joint committees to oversee manufacturing, commercial andpandemic planning for the product. Gilead will also have the option toco-promote Tamiflu in specialized areas in the United States. Gileadwill not co-promote Tamiflu in 2006 and has not yet determined whetherit will exercise its option for co-promotion in 2007 or beyond.

"The global threat of a potential avian flu pandemic haschallenged governments, public health officials and the pharmaceuticalindustry to join together in partnership for the purpose ofestablishing a comprehensive plan to combat this deadly disease.Beyond this threat, seasonal influenza outbreaks result in hundreds ofthousands of deaths each year around the world. We have ended ourdispute with Roche in an effort to work together, with the utmostdiligence, to address this global public health need," said John C.Martin, PhD, President and Chief Executive Officer, Gilead Sciences."As the inventor and the company that devised the manufacturingprocess for Tamiflu, Gilead looks forward to partnering our expertisewith that of Roche, serving as an additional resource to support thisimportant product."

William M. Burns, CEO Roche Pharmaceuticals Division, commented:"The redefined agreement with Gilead is an important step. Together,Roche and Gilead will be able to focus their efforts even more onmaking sure that the needs for this medicine can be met, both for thetreatment and prevention of seasonal influenza as well as for theworldwide stockpiling for pandemic plans."

Gilead receives a blended royalty on sales of Tamiflu, tiered from14 to 22 percent based on Roche's annual net sales. Roche has agreedto eliminate the pre-existing contractual cost of goods adjustmentsfrom the royalty calculations, retroactive to calendar year 2004 andfor all future calculations. As a result of the elimination of thecost of goods adjustment, Roche will begin to pay Gilead at thecontractually specified royalty rate based on the level of salesachieved, instead of the prior year's effective royalty rate. Withoutthe cost of goods adjustments, based on actual sales for the firstnine months of 2005 and estimated pandemic sales for the fourthquarter, Gilead anticipates receiving a blended royalty for Roche'sfull year 2005 Tamiflu sales in the range of 18 to 19 percent. Within15 days after the amendment becomes effective, Roche will pay Gilead$62.5 million to reimburse Gilead for cost of goods adjustmentsretroactive to 2004 as well as to update the royalties payable toGilead for the first nine months of 2005 based on current year royaltyrates. Finally, Roche has agreed to waive its rights on the $18.2million that Roche previously paid to Gilead and that Gilead deferred,for the disputed royalty calculations in the period from 2001 through2003, as outlined in the notice of termination delivered to Roche onJune 23, 2005.

Conference Call

At 8:30 a.m. Eastern Time today, Gilead will webcast a conferencecall live on the company's website to discuss this announcement. Toaccess the live webcast or the archive via the internet, log on towww.gilead.com. Alternatively, please call 800-706-7749 (U.S.) or617-614-3474 (international) and dial the participant passcode36381347 to access the call. Telephone replay is availableapproximately two hours after the call through 7:30 a.m. Eastern Time,November 19, 2005. To access the replay, please call 888-286-8010(U.S.) or 617-801-6888 (international) and dial the participantpasscode 85062101. This webcast will be archived on www.gilead.com forthree days. Please connect to the company's website at least 15minutes prior to the conference call to ensure adequate time for anysoftware download that may be needed to hear the webcast.

About Influenza

In a typical flu season, approximately 5-15 percent of thepopulation develops upper respiratory infections that are caused bythe influenza virus. These annual epidemics are believed to result in3-5 million cases of severe illness and 250-500,000 deaths worldwide.In the United States alone, up to 40 million Americans develop theflu, more than 200,000 people are hospitalized and 36,000 people dieas a result of the flu and its complications during the average fluseason.

While influenza is a significant public health issue in a typicalyear, the outbreak of pandemic influenza has the potential to causetens of millions of deaths around the world. The Centers for DiseaseControl and Prevention (CDC) predict that an influenza pandemic in theUnited States would cause 20-47 million illnesses, 730,000hospitalizations and 89-207,000 deaths.

About Tamiflu

Tamiflu is indicated for the treatment and prevention of the mostcommon strains of influenza (types A and B). The medication targetsone of the two major surface structures of the influenza virus, theneuraminidase protein. The neuraminidase site is virtually the same inthe most common strains of influenza, types A and B. Tamiflu attacksthe influenza virus and is thought to work by stopping it fromspreading inside the body.

Tamiflu is generally well tolerated. In treatment studies inadults, the most frequently reported adverse events weremild-to-moderate transient nausea or vomiting. Other events reportedmore frequently than with placebo were bronchitis, insomnia andvertigo. In prophylaxis studies in patients aged 13 and older, adverseevents were qualitatively similar to those seen in the treatmentstudies despite a longer duration of dosing. Events reported morefrequently in subjects receiving Tamiflu compared to subjectsreceiving placebo in prophylaxis studies included nausea, vomiting,diarrhea, abdominal pain, dizziness, insomnia, headache, vertigo andfatigue.

In pediatric treatment studies, the most frequently reportedadverse event was vomiting. Other events reported more frequently bypediatric patients treated with Tamiflu included abdominal pain,epistaxis, ear disorder and conjunctivitis. These events generallyoccurred once and resolved despite continued dosing. In a prophylaxisstudy, which included pediatric patients aged one to 12 years,gastrointestinal events were most frequently reported, particularlyvomiting.

Efficacy of Tamiflu in the treatment of subjects with chroniccardiac disease and/or respiratory disease has not been established.

Vaccination is considered the first line of defense againstinfluenza.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers,develops and commercializes innovative therapeutics in areas of unmetmedical need. The company's mission is to advance the care of patientssuffering from life-threatening diseases worldwide. Headquartered inFoster City, California, Gilead has operations in North America,Europe and Australia. For more information regarding Gilead, pleasevisit www.gilead.com.

About Roche

Headquartered in Basel, Switzerland, Roche is one of the world'sleading research-focused healthcare groups in the fields ofpharmaceuticals and diagnostics. As a supplier of innovative productsand services for the early detection, prevention, diagnosis andtreatment of diseases, the Group contributes on a broad range offronts to improving people's health and quality of life. Roche is aworld leader in diagnostics, the leading supplier of drugs for cancerand transplantation and a market leader in virology. In 2004 sales bythe Pharmaceuticals Division totaled 21.7 billion Swiss francs, whilethe Diagnostics Division posted sales of 7.8 billion Swiss francs.Roche employs roughly 65,000 people in 150 countries and has R&Dagreements and strategic alliances with numerous partners, includingmajority ownership interests in Genentech and Chugai. Additionalinformation about the Roche Group is available on the Internet(www.roche.com).

Securities Safe Harbor Under the Private Securities LitigationReform Act of 1995

This press release contains "forward-looking statements" as thatterm is defined in the Private Securities Litigation Reform Act of1995. These statements involve known and unknown risks anduncertainties, which may cause actual results to differ materiallyfrom those set forth in such statements. Such forward-lookingstatements include, without limitation, statements relating toGilead's expected range of royalties on net sales of Tamiflu and theCDC's predictions regarding the effects of a potential influenzapandemic in the United States. Forward-looking statements also includeother statements of management's opinion or expectations. Noforward-looking statement can be guaranteed, and actual results maydiffer materially from those projected due to, among other things, theability for Roche and Gilead to effectively work together inoverseeing the global manufacturing, licensing, commercialization andpromotion of Tamiflu, as well as other scientific and medicalinitiatives, whether there is an actual or perceived need for Tamiflubased on concerns of a potential flu pandemic, the actual amount ofTamiflu sold, whether Tamiflu can effectively combat the avian flu,marketing effectiveness, as well as changes in economic, business,competitive, technological or regulatory factors and trends. Allforward-looking statements in this document are made as of the datehereof, based on information available to Gilead as of the date hereofand Gilead undertakes no obligation to publicly update anyforward-looking statement in order to reflect events or circumstancesthat arise after the date of this release. Forward-looking statementsin this press release should be evaluated together with, and actualresults may be affected by, the many uncertainties that affectGilead's business, particularly those mentioned in Gilead's Form 10-Kfor the year ended December 31, 2004, and in periodic reports on Form10-Q and Form 8-K, including but not limited to those described inGilead's Form 10-Q for the quarterly period ended September 30, 2005under the captions "Forward-Looking Statements and Risk Factors."

For more information on Gilead Sciences, please visitwww.gilead.com or call the Gilead Public Affairs Department at1-800-GILEAD-5 (1-800-445-3235).