Prepared by MERRILL CORPORATION

Filed Pursuant to
Rule 424 (b) (3) and (c)
File No. 333-54350

GILEAD SCIENCES, INC.

$250,000,000 Principal Amount
5% Convertible Subordinated Notes due December 15, 2007
and Shares of Common Stock Issuable upon Conversion of the Notes

    This prospectus supplement should be read in conjunction with the prospectus dated February 9, 2001, which is to be delivered with this prospectus supplement.

    See "Risk Factors" beginning on page 6 of the prospectus to read about factors you should consider before buying the notes or our common stock.

    Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

    The table and related notes, and the paragraph immediately following the table and related notes, appearing in the prospectus under the heading "Selling Securityholders" is superseded by the following table and related notes, and the following paragraph immediately following the table and related notes:

Name
   Principal
Amount of
Notes
Beneficially
Owned and
Offered(1)
   Common Stock
Beneficially
Owned(2)
   Common
Stock
Offered
   Principal
Amount of
Notes Owned
After
Completion of
Offering
   Common Stock
Owned After
Completion of
Offering
1976 Distribution Trust FBO A.R. Lander / Zinterhofer   14,000   284   284   0   0
1976 Distribution Trust FBO Jane A. Lander   14,000   284   284   0   0
AAM / Zazove Institutional Income Fund, L.P. (BS)   1,000,000   20,356   20,356   0   0
AFTRA Health Fund   75,000   1,526   1,526   0   0
Alexandra Global Investment Fund 1, Ltd.   2,500,000   50,890   50,890   0   0
American Motorist Insurance Company   489,000   9,954   9,954   0   0
Arapahoe County Colorado   48,000   977   977   0   0
Argent Classic Convertible Arbitrage Fund (Bermuda) Ltd.   7,000,000   142,493   142,493   0   0
Argent Convertible Arbitrage Fund Ltd.   4,000,000   81,424   81,424   0   0
BP Amoco PLC, Master Trust   1,072,000   21,821   21,821   0   0
British Virgin Islands Social Security Board   36,000   732   732   0   0
Brown & Williamson Tobacco Retirement Trust   25,000   508   508   0   0
Century National Insurance Company   500,000   10,178   10,178   0   0
City of New Orleans   201,000   4,091   4,091   0   0
Deutsche Banc Alex Brown Inc   15,125,000   307,888   307,888   0   0
Employee Benefit Convertible Securities Fund (Custodian DTC #955 Bank of America Personal Trust)   250,000   5,089   5,089   0   0
Fidelity Financial Trust: Fidelity Convertible Securities Fund   5,500,000   111,959   111,959   0   0
First Union Securities Inc.   2,000,000   40,712   40,712   0   0
FIST Convertible Securities Fund   1,500,000   30,534   30,534   0   0
Forest Alternative Strategies Fund II L.P. ASM   25,000   508   508   0   0
Forest Global Convertible Fund A-5   1,755,000   35,725   35,725   0   0
HFR Master Fund Ltd.   120,000   2,442   2,442   0   0
Highbridge International LLC   6,852,000   139,480   139,480   0   0
Hotel Union & Hotel Industry of Hawaii   373,000   7,592   7,592   0   0
Jefferies & Company Inc.   8,000   162   162   0   0
JMG Capital Partners, LP   3,500,000   71,246   71,246   0   0
JMG Triton Offshore Fund Ltd.   3,500,000   71,246   71,246   0   0

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J.P. Morgan Securities, Inc.   500,000   10,178   10,178   0   0
KBC Financial Products USA   2,500,000   50,890   50,890   0   0
Lehman Brothers Inc.   20,000,000   407,124   407,124   0   0
Lipper Convertibles L.P.   1,000,000   20,356   20,356   0   0
LLT Limited   100,000   2,035   2,035   0   0
Local Initiatives Support Corporation   46,000   936   936   0   0
Mainstay Convertible Fund   1,400,000   28,498   28,498   0   0
Mainstay VP Convertible Portfolio   350,000   7,124   7,124   0   0
Merrill Lynch Insurance Group   246,000   5,007   5,007   0   0
Morgan Stanley & Co.   35,000,000   712,468   712,468   0   0
Nabisco Holdings   29,000   590   590   0   0
Nations Convertible Securities Fund (Custodian DTC #901 Bank of New York)   6,150,000   125,190   125,190   0   0
New Orleans Firefighters Pension / Relief Fund   106,000   2,157   2,157   0   0
New York Life Insurance and Annuity Corporation   1,000,000   20,356   20,356   0   0
New York Life Insurance Company   9,000,000   183,206   183,206   0   0
New York Life Separate Account #7   150,000   3,053   3,053   0   0
Occidental Petroleum Corporation   194,000   3,949   3,949   0   0
Oppenheimer Convertible Securities Fund   4,000,000   81,424   81,424   0   0
Pacific Life Insurance Company   1,000,000   20,356   20,356   0   0
Parker-Hannifin Corporation   37,000   753   753   0   0
Pro-Mutual   685,000   13,944   13,944   0   0
Putnam Asset Allocation Funds-Balanced Portfolio   150,000   3,053   3,053   0   0
Putnam Asset Allocation Funds-Conservative Portfolio   89,000   1,811   1,811   0   0
Putnam Convertible Income-Growth Trust   2,000,000   40,712   40,712   0   0
Putnam Convertible Opportunities and Income Trust   49,000   997   997   0   0
Putnam High Income Convertible and Bond Fund   300,000   6,106   6,106   0   0
Raytheon Master Pension Trust   529,000   10,768   10,768   0   0
RBC Capital Services, Inc. c/o Forest Investment Mngt., L.L.C.   20,000   407   407   0   0
RJR Reynolds   92,000   1,872   1,872   0   0
Robertson Stephens   6,000,000   122,137   122,137   0   0
R2 Investments, LDC   17,500,000   356,234   356,234   0   0
San Diego County Employees Retirement Association   2,100,000   42,748   42,748   0   0
SG Cowen Securities Corporation   2,000,000   40,712   40,712   0   0
Shell Pension Trust   428,000   8,712   8,712   0   0

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Smithfield Trust Company   10,000   203   203   0   0
State of Maryland Retirement System   2,509,000   51,073   51,073   0   0
The City University of New York   119,000   2,422   2,422   0   0
The Grable Foundation   91,000   1,852   1,852   0   0
The Grady Hospital Foundation   103,000   2,096   2,096   0   0
Tribeca Investment LLC   8,000,000   162,849   162,849   0   0
University of Rochester   19,000   386   386   0   0
Viacom Inc. Pension Plan Master Trust   47,000   956   956   0   0
Zurich Master Hedge Fund c/o Forest Investment Mngt., L.L.C.   100,000   2,035   2,035   0   0
(1)
Amounts indicated may be in excess of the total amount registered due to sales or transfers exempt from the registration requirements of the Securities Act since the date upon which the selling holders provided to us the information regarding their notes and common stock.

(2)
Unless otherwise noted, represents shares of common stock issuable upon conversion of notes.

    With the exception of J.P. Morgan Securities, Inc., Lehman Brothers Inc. and Morgan Stanley & Co., none of the selling holders nor any of their affiliates, officers, directors or principal equity holders has held any position or office or has had any material relationship with us within the past three years. J. P. Morgan Securities, Inc., Lehman Brothers Inc. and Morgan Stanley & Co. were initial purchasers of the notes. The selling holders purchased the notes in private transactions on or after December 13, 2000.

The date of this prospectus supplement is May 15, 2001.

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