<PAGE>


                                                                     Exhibit 4.2



                          REGISTRATION RIGHTS AGREEMENT

                          Dated as of December 18, 2000

                                  By and Among

                             GILEAD SCIENCES, INC.,

                                    as Issuer

                                       and

                          J.P. MORGAN SECURITIES INC.,

                             CHASE SECURITIES INC.,

                              LEHMAN BROTHERS INC.

                                       and

                        MORGAN STANLEY & CO. INCORPORATED

                              as Initial Purchasers

                   5% Convertible Subordinated Notes Due 2007


<PAGE>


<TABLE>
<CAPTION>

                                TABLE OF CONTENTS

                                                                           PAGE
                                                                           ----
<S>   <C>                                                                    <C>
1.     Definitions............................................................1
2.     Shelf Registration.....................................................4
3.     Liquidated Damages.....................................................5
4.     Registration Procedures................................................7
5.     Registration Expenses.................................................14
6.     Indemnification.......................................................14
7.     Rules 144 and 144A....................................................18
8.     Underwritten Registrations............................................18
9.     Miscellaneous.........................................................18
       (a)    No Inconsistent Agreements.....................................18
       (b)    Adjustments Affecting Registrable Securities...................19
       (c)    Amendments and Waivers.........................................19
       (d)    Notices........................................................19
       (e)    Successors and Assigns.........................................20
       (f)    Counterparts...................................................20
       (g)    Headings.......................................................20
       (h)    Governing Law..................................................20
       (i)    Severability...................................................21
       (j)    Securities Held by the Company or Its Affiliates...............21
       (k)    Third Party Beneficiaries......................................21
       (l)    Entire Agreement...............................................21
</TABLE>


                                      -i-


<PAGE>


                          REGISTRATION RIGHTS AGREEMENT


            This Registration Rights Agreement (the "AGREEMENT") is dated as of
December 18, 2000, by and among GILEAD SCIENCES, INC., a Delaware corporation
(the "COMPANY"), J.P. MORGAN SECURITIES INC., CHASE SECURITIES INC., LEHMAN
BROTHERS INC. and MORGAN STANLEY & CO. INCORPORATED (individually, an "INITIAL
PURCHASER," and together, the "INITIAL PURCHASERS").

            This Agreement is entered into in connection with the Purchase
Agreement, dated as of December 13, 2000 (the "PURCHASE AGREEMENT"), by and
among the Company and the Initial Purchasers, which provides for the sale by the
Company to the Initial Purchasers of $250,000,000 aggregate principal amount of
the Company's 5% Convertible Subordinated Notes Due 2007 (the "FIRM NOTES"),
which are convertible into Common Stock of the Company, par value $.001 per
share (the "UNDERLYING SHARES"), plus up to an additional $50,000,000 aggregate
principal amount of the same which the Initial Purchasers may subsequently elect
to purchase pursuant to the terms of the Purchase Agreement (the "ADDITIONAL
NOTES" and together with the Firm Notes, the "CONVERTIBLE NOTES"). The Notes are
being issued pursuant to an indenture dated as of the date hereof (the
"INDENTURE"), between the Company and Chase Manhattan Bank and Trust Company,
National Association, as Trustee.

            In order to induce the Initial Purchasers to enter into the Purchase
Agreement, the Company has agreed to provide the registration rights set forth
in this Agreement for the benefit of the Initial Purchasers and any subsequent
holder or holders of the Convertible Notes or Underlying Shares. The execution
and delivery of this Agreement is a condition to the Initial Purchasers'
obligation to purchase the Firm Notes under the Purchase Agreement.

            The parties hereby agree as follows:

1.   DEFINITIONS.
     -----------

            As used in this Agreement, the following terms shall have the
following meanings:

            AGREEMENT: See the first introductory paragraph hereto.

            AMOUNT OF REGISTRABLE SECURITIES: (a) With respect to Convertible
Notes constituting Registrable Securities, the aggregate principal amount of all
such Convertible Notes outstanding, (b) with respect to Underlying Shares
constituting Registrable Securities, the aggregate number of such Underlying
Shares outstanding multiplied by the Conversion Price (as defined in the
Indenture relating to the Convertible Notes upon the conversion of which such
Underlying Shares were issued) in effect at the time of computing the Amount of
Registrable Securities or, if no such Convertible Notes are then outstanding,
the last Conversion Price that was in effect under such Indenture when any such
Convertible Notes were last outstanding,


<PAGE>



and (c) with respect to combinations thereof, the sum of (a) and (b) for the
relevant Registrable Securities.

            BUSINESS DAY: Any day that is not a Saturday, Sunday or a day on
which banking institutions in New York are authorized or required by law to be
closed.

            CLOSING DATE: December 18, 2000.

            COMPANY: See the first introductory paragraph hereto.

            CONVERTIBLE NOTES: See the second introductory paragraph hereto.

            COUNSEL TO THE HOLDERS: See Section 5(b) hereof.

            DAMAGES PAYMENT DATE: See Section 3(c) hereof.

            DEPOSITARY: The Depository Trust Company until a successor is
appointed by the Company.

            EFFECTIVENESS DATE: The 180th day after the Closing Date.

            EFFECTIVENESS PERIOD: See Section 2 hereof.

            EXCHANGE ACT: The Securities Exchange Act of 1934, as amended, and
the rules and regulations of the SEC promulgated thereunder.

            FILING DATE: The 90th day after the Closing Date.

            HOLDER: Any holder of Registrable Securities.

            INDEMNIFIED HOLDER: See Section 6 hereof.

            INDEMNIFIED PERSON: See Section 6 hereof.

            INDEMNIFYING PERSON: See Section 6 hereof.

            INDENTURE: See the second introductory paragraph hereto.

            INITIAL PURCHASERS: See the first introductory paragraph hereto.

            INITIAL SHELF REGISTRATION: See Section 2(a) hereof.

            INSPECTORS: See Section 4(n) hereof.

            LIQUIDATED DAMAGES: See Section 3(a) hereof.


                                      -2-

<PAGE>

            NASD: See Section 4(q) hereof.

            PERSON: An individual, partnership, corporation, limited liability
company, unincorporated association, trust or joint venture, or a governmental
agency or political subdivision thereof.

            PROSPECTUS: The prospectus included in any Registration Statement
(including, without limitation, any prospectus subject to completion and a
prospectus that includes any information previously omitted from a prospectus
filed as part of an effective registration statement in reliance upon Rule 430A
promulgated under the Securities Act), as amended or supplemented by any
prospectus supplement, and all other amendments and supplements to the
Prospectus, including post-effective amendments, and all material incorporated
by reference or deemed to be incorporated by reference in such Prospectus.

            PURCHASE AGREEMENT: See the second introductory paragraph hereto.

            RECORDS: See Section 4(n) hereof.

            REGISTRABLE SECURITIES: All Convertible Notes and all Underlying
Shares upon original issuance thereof and at all times subsequent thereto until
the earliest to occur of (i) a Registration Statement covering such Convertible
Notes and Underlying Shares having been declared effective by the SEC and such
Convertible Notes and Underlying Shares have been disposed of in accordance with
such effective Registration Statement, (ii) such Convertible Notes and
Underlying Shares having been sold in compliance with Rule 144 or could (except
with respect to affiliates of the Company within the meaning of the Securities
Act) be sold in compliance with Rule 144(k), or (iii) such Convertible Notes and
any Underlying Shares cease to be outstanding.

            REGISTRATION DEFAULT: See Section 3(a) hereof.

            REGISTRATION STATEMENT: Any registration statement of the Company
filed with the SEC pursuant to the provisions of this Agreement, including the
Prospectus, amendments and supplements to such registration statement, including
post-effective amendments, all exhibits and all material incorporated by
reference or deemed to be incorporated by reference in such registration
statement.

            RULE 144: Rule 144 promulgated under the Securities Act, as such
Rule may be amended from time to time, or any similar rule (other than Rule
144A) or regulation hereafter adopted by the SEC providing for offers and sales
of securities made in compliance therewith resulting in offers and sales by
subsequent holders that are not affiliates of an issuer of such securities being
free of the registration and prospectus delivery requirements of the Securities
Act.


                                      -3-

<PAGE>


            RULE 144A: Rule 144A promulgated under the Securities Act, as such
Rule may be amended from time to time, or any similar rule (other than Rule 144)
or regulation hereafter adopted by the SEC.

            RULE 415: Rule 415 promulgated under the Securities Act, as such
Rule may be amended from time to time, or any similar rule or regulation
hereafter adopted by the SEC.

            SEC: The Securities and Exchange Commission.

            SECURITIES ACT: The Securities Act of 1933, as amended, and the
rules and regulations of the SEC promulgated thereunder.

            SHELF REGISTRATION: See Section 2(b) hereof.

            SHELF REGISTRATION STATEMENT: See Section 2(b) hereof.

            SUBSEQUENT SHELF REGISTRATION: See Section 2(b) hereof.

            TIA: The Trust Indenture Act of 1939, as amended, and the rules and
regulations of the SEC promulgated thereunder.

            TRUSTEE: The Trustee under the Indenture.

            UNDERLYING SHARES: See the second introductory paragraph hereto.

            UNDERWRITTEN REGISTRATION OR UNDERWRITTEN OFFERING: A registration
in which securities of the Company are sold to an underwriter for reoffering to
the public.

2.   SHELF REGISTRATION

            (a)   SHELF REGISTRATION. The Company shall as promptly as
reasonably practicable file with the SEC a Registration Statement for an
offering to be made on a continuous basis pursuant to Rule 415 covering all of
the Registrable Securities (the "INITIAL SHELF REGISTRATION"). The Company shall
use its reasonable best efforts to file with the SEC the Initial Shelf
Registration on or prior to the Filing Date. The Initial Shelf Registration
shall be on Form S-3 or another appropriate form permitting registration of such
Registrable Securities for resale by Holders in the manner or manners designated
by them (including, without limitation, one or more underwritten offerings). The
Company shall not permit any securities other than the Registrable Securities to
be included in the Initial Shelf Registration or any Subsequent Shelf
Registration (as defined below).

            The Company shall use its reasonable best efforts to cause the
Initial Shelf Registration to be declared effective under the Securities Act on
or prior to the Effectiveness Date and to keep such Initial Shelf Registration
continuously effective under the Securities


                                      -4-


<PAGE>

Act until the date that is two years from the Closing Date (as it may be
shortened pursuant to clause (i) or clause (ii) immediately following, the
"EFFECTIVENESS PERIOD"), or such shorter period ending when (i) all the shares
of Registrable Securities covered by the Initial Shelf Registration have been
sold in the manner set forth and as contemplated in the Initial Shelf
Registration, (ii) the date on which all the Registrable Securities (x) held by
Persons who are not affiliates of the Company may be resold pursuant to Rule
144(k) under the Securities Act or (y) cease to be outstanding, or (iii) a
Subsequent Shelf Registration covering all of the Registrable Securities has
been declared effective under the Securities Act.

            (b)   SUBSEQUENT SHELF REGISTRATIONS. If the Initial Shelf
Registration or any Subsequent Shelf Registration ceases to be effective for any
reason at any time during the Effectiveness Period (other than because of the
sale of all of the securities registered thereunder), the Company shall use its
reasonable best efforts to obtain the prompt withdrawal of any order suspending
the effectiveness thereof, and in any event shall within 45 days of such
cessation of effectiveness amend the Initial Shelf Registration in a manner to
obtain the withdrawal of the order suspending the effectiveness thereof, or file
an additional "shelf" Registration Statement pursuant to Rule 415 covering all
of the Registrable Securities (a "SUBSEQUENT SHELF REGISTRATION"). If a
Subsequent Shelf Registration is filed, the Company shall use its reasonable
best efforts to cause the Subsequent Shelf Registration to be declared effective
under the Securities Act as soon as practicable after such filing and to keep
such Registration Statement continuously effective for a period equal to the
number of days in the Effectiveness Period less the aggregate number of days
during which the Initial Shelf Registration or any Subsequent Shelf Registration
was previously continuously effective. As used herein the term "SHELF
REGISTRATION" means the Initial Shelf Registration and any Subsequent Shelf
Registration and the term "SHELF REGISTRATION STATEMENT" means any Registration
Statement filed in connection with a Shelf Registration.

            (c)   SUPPLEMENTS AND AMENDMENTS. The Company shall promptly
supplement and amend the Shelf Registration if required by the rules,
regulations or instructions applicable to the registration form used for such
Shelf Registration, if required by the Securities Act, or if reasonably
requested by the Holders of the majority in Amount of Registrable Securities
covered by such Registration Statement or by any underwriter of such Registrable
Securities.

3.   LIQUIDATED DAMAGES

            (a)   The Company and the Initial Purchasers agree that the Holders
of Registrable Securities will suffer damages if the Company fails to fulfill
its obligations under Section 2 hereof and that it would not be feasible to
ascertain the extent of such damages with precision. Accordingly, the Company
agrees to pay liquidated damages on the Registrable Securities ("LIQUIDATED
DAMAGES") under the circumstances and to the extent set forth below (each of
which shall be given independent effect; each a "REGISTRATION DEFAULT"):


                                      -5-


<PAGE>

            (i)   if the Initial Shelf Registration is not filed on or prior to
the Filing Date, then commencing on the day after the Filing Date, Liquidated
Damages shall accrue on the Registrable Securities at a rate of 0.50% per annum
on the Amount of Registrable Securities for the first 90 days immediately
following the Filing Date, such Liquidated Damages increasing by an additional
0.50% per annum at the beginning of each subsequent 90-day period;

            (ii)  if the Initial Shelf Registration is not declared effective by
the SEC on or prior to the Effectiveness Date, then commencing on day after the
Effectiveness Date, Liquidated Damages shall accrue on the Registrable
Securities at a rate of 0.50% per annum on the Amount of Registrable Securities
for the first 90 days immediately following the day after such Effectiveness
Date, such Liquidated Damages increasing by an additional 0.50% per annum at the
beginning of each subsequent 90-day period; and

            (iii) if a Shelf Registration has been declared effective and such
Shelf Registration ceases to be effective at any time during the Effectiveness
Period (other than as permitted under Section 3(b)), then Liquidated Damages
shall accrue on the Registrable Securities at a rate of 0.50% per annum on the
Amount of Registrable Securities for the first 90 days commencing on the day
such Shelf Registration ceases to be effective, such Liquidated Damages
increasing by an additional 0.50% per annum at the beginning of each such
subsequent 90-day period;

PROVIDED, HOWEVER, that Liquidated Damages on the Registrable Securities may not
accrue under more than one of the foregoing clauses (i), (ii) or (iii) at any
one time and at no time shall the aggregate amount of Liquidated Damages
accruing exceed in the aggregate 1.0% per annum of the Amount of Registrable
Securities; PROVIDED, FURTHER, HOWEVER, that (1) upon the filing of the Shelf
Registration as required hereunder (in the case of clause (a)(i) of this Section
3), (2) upon the effectiveness of the Shelf Registration as required hereunder
(in the case of clause (a)(ii) of this Section 3), or (3) upon the effectiveness
of a Shelf Registration which had ceased to remain effective (in the case of
(a)(iii) of this Section 3), Liquidated Damages on the Registrable Securities as
a result of such clause (or the relevant subclause thereof), as the case may be,
shall cease to accrue. It is understood and agreed that, notwithstanding any
provision to the contrary, (i) so long as any Registrable Security is then
covered by an effective Shelf Registration Statement, no Liquidated Damages
shall accrue on such Registrable Security and (ii) no Holder shall be entitled
to Liquidated Damages hereunder unless such Holder has complied with its
obligations to furnish the information required by the second paragraph of
Section 4(s) hereof. The Liquidated Damages provided for in this Section 3 shall
be a Holder's exclusive remedy in the event of a Registration Default.

            (b)   Notwithstanding paragraph (a) of this Section 3, the Company
shall be permitted to suspend the effectiveness of a Shelf Registration for up
to 30 consecutive days in any 90 day period, for a total of not more than 60
days in any 365 day period, without paying Liquidated Damages.


                                      -6-

<PAGE>

            (c)   So long as Convertible Notes remain outstanding, the Company
shall notify the Trustee within two Business Days after each and every date on
which an event occurs in respect of which Liquidated Damages is required to be
paid. Any amounts of Liquidated Damages due pursuant to (a)(i), (a)(ii) or
(a)(iii) of this Section 3 will be payable in cash semi-annually on each May 15
and December 15 (each a "DAMAGES PAYMENT DATE"), commencing with the first such
date occurring after any such Liquidated Damages commences to accrue, to Holders
to whom regular interest is payable on such Damages Payment Date with respect to
Convertible Notes that are Registrable Securities and to Persons that are
registered Holders 15 days prior to such Damages Payment Date with respect to
Underlying Shares that are Registrable Securities. The amount of Liquidated
Damages for Registrable Securities will be determined by multiplying the
applicable rate of Liquidated Damages by the Amount of Registrable Securities
outstanding on the Damages Payment Date following such Registration Default in
the case of the first such payment of Liquidated Damages with respect to a
Registration Default (and thereafter at the next succeeding Damages Payment Date
until the cure of such Registration Default), multiplied by a fraction, the
numerator of which is the number of days such Liquidated Damages rate was
applicable during such period (determined on the basis of a 360-day year
comprised of twelve 30-day months and, in the case of a partial month, the
actual number of days elapsed), and the denominator of which is 360.

4.    REGISTRATION PROCEDURES

            In connection with the filing of any Registration Statement pursuant
to Section 2 hereof, the Company shall effect such registrations to permit the
resale of the securities covered thereby in accordance with the intended method
or methods of disposition thereof, and pursuant thereto and in connection with
any Registration Statement filed by the Company hereunder the Company shall:

            (a)   Prepare and file with the SEC on or prior to the Filing Date,
a Registration Statement or Registration Statements as prescribed by Section 2
hereof, and use its reasonable best efforts to cause each such Registration
Statement to become effective and remain effective as provided herein; PROVIDED,
HOWEVER, that before filing any Registration Statement or Prospectus or any
amendments or supplements thereto, the Company shall furnish to and afford the
Holders of the Registrable Securities that have provided the information
required by the second paragraph of Section 4(s), Counsel to the Holders and the
managing underwriters, if any, a reasonable opportunity to review copies of all
such documents proposed to be filed (in each case, where possible, at least five
Business Days prior to such filing, or such later date as is reasonable under
the circumstances). The Company shall not file any Registration Statement or
Prospectus or any amendments or supplements thereto if the Holders of a majority
in Amount of Registrable Securities that have provided the information required
by the second paragraph of Section 4(s), Counsel to the Holders or the managing
underwriters, if any, shall reasonably object.


                                      -7-

<PAGE>


            (b)   Prepare and file with the SEC such amendments and
post-effective amendments to each Shelf Registration, as may be necessary to
keep such Registration Statement continuously effective for the Effectiveness
Period; cause the related Prospectus to be supplemented by any Prospectus
supplement required by applicable law, and as so supplemented to be filed
pursuant to Rule 424 (or any similar provisions then in force) promulgated under
the Securities Act; and comply with the provisions of the Securities Act and the
Exchange Act applicable to it with respect to the disposition of all securities
covered by such Registration Statement as so amended or in such Prospectus as so
supplemented. The Company shall be deemed not to have used its reasonable best
efforts to keep a Registration Statement effective during the Effectiveness
Period if it voluntarily takes any action that would result in selling Holders
of the Registrable Securities covered thereby not being able to sell such
Registrable Securities during that period unless such action is required by
applicable law or unless the Company complies with this Agreement, including
without limitation the provisions of Sections 3(b) and 4(k) hereof.

            (c)   Notify the selling Holders of Registrable Securities (which
Holders shall have provided the information required pursuant to the second
paragraph of Section 4(s) hereof), Counsel to the Holders and the managing
underwriters, if any, promptly (but in any event within two Business Days) and,
if requested by such persons, confirm such notice in writing, (i) when a
Prospectus or any prospectus supplement or post-effective amendment has been
filed, and, with respect to a Registration Statement or any post-effective
amendment, when the same has become effective under the Securities Act
(including in such notice a written statement that any Holder may, upon request,
obtain, at the sole expense of the Company, one conformed copy of such
Registration Statement or post-effective amendment including financial
statements and schedules, documents incorporated or deemed to be incorporated by
reference and exhibits), (ii) of the issuance by the SEC of any stop order
suspending the effectiveness of a Registration Statement or of any order
preventing or suspending the use of any preliminary prospectus or the initiation
of any proceedings for that purpose, (iii) of the happening of any event, the
existence of any condition or any information becoming known that makes any
statement made in such Registration Statement or related Prospectus or any
document incorporated or deemed to be incorporated therein by reference untrue
in any material respect or that requires the making of any changes in or
amendments or supplements to such Registration Statement, Prospectus or
documents so that, in the case of the Registration Statement, it will not
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading, and that in the case of the Prospectus, it will not contain any
untrue statement of a material fact or omit to state any material fact required
to be stated therein or necessary to make the statements therein, in the light
of the circumstances under which they were made, not misleading and (iv) of the
Company's determination that a post-effective amendment to a Registration
Statement would be appropriate.

            (d)   Use its reasonable best efforts to prevent the issuance of any
order suspending the effectiveness of a Registration Statement or of any order
preventing or suspending


                                      -8-


<PAGE>


the use of a Prospectus and, if any such order is issued, to use its reasonable
best efforts to obtain the withdrawal of any such order at the earliest possible
moment.

            (e)   In the event of an underwritten offering pursuant to the terms
of this Agreement, if requested by the managing underwriter or underwriters (if
any) or the Holders of the majority in Amount of Registrable Securities being
sold in connection with such underwritten offering (i) promptly incorporate in a
prospectus supplement or, if required, a post-effective amendment such
information as the managing underwriter or underwriters (if any), such Holders
or counsel for any of them reasonably determine is necessary to be included
therein, (ii) make all required filings of such prospectus supplement or such
post-effective amendment as soon as reasonably practicable after the Company has
received notification of the matters to be incorporated in such prospectus
supplement or post-effective amendment and (iii) supplement or make amendments
to such Registration Statement.

            (f)   Make available to each selling Holder of Registrable
Securities who so requests, Counsel to the Holders and each managing
underwriter, if any, at the sole expense of the Company, one conformed copy of
the Registration Statement or Registration Statements and each post-effective
amendment thereto, including financial statements and schedules, and all
documents incorporated or deemed to be incorporated therein by reference and all
exhibits.

            (g)   Deliver to each selling Holder of Registrable Securities,
Counsel to the Holders and the underwriters, if any, at the sole expense of the
Company, as many copies of the Prospectus (including each form of preliminary
prospectus) and each amendment or supplement thereto and any documents
incorporated by reference therein as such Persons may reasonably request; and,
subject to compliance by selling Holders with the second paragraph of Section
4(s) hereof, the Company hereby consents to the use of such Prospectus and each
amendment or supplement thereto in accordance with this Agreement by each of the
selling Holders of Registrable Securities and the underwriters or agents, if
any, and dealers (if any), in connection with the offering and sale of the
Registrable Securities covered by such Prospectus and any amendment or
supplement thereto.

            (h)   Prior to any public offering of Registrable Securities, to use
its reasonable best efforts to register or qualify, to the extent required by
applicable law, and to cooperate with the selling Holders of Registrable
Securities, the managing underwriter or underwriters, if any, and their
respective counsel in connection with the registration or qualification (or
exemption from such registration or qualification) of such Registrable
Securities or offer and sale under the securities or Blue Sky laws of such
jurisdictions within the United States as any selling Holder, or the managing
underwriter or underwriters, if any, reasonably request; PROVIDED, HOWEVER, that
where Registrable Securities are offered other than through an underwritten
offering, the Company agrees to cause the Company's counsel to perform Blue Sky
investigations and file registrations and qualifications required to be filed
pursuant to this Section 4(h); keep each such registration or qualification (or
exemption therefrom) effective during the period such Registration Statement is
required to be kept effective and do any and


                                      -9-

<PAGE>


all other acts or things reasonably necessary or advisable to enable the
disposition in such jurisdictions of the Registrable Securities covered by the
applicable Registration Statement; PROVIDED, HOWEVER, that the Company shall not
be required to (A) qualify generally to do business in any jurisdiction where it
is not then so qualified, (B) take any action that would subject it to general
service of process in any such where it is not then so subject or (C) subject
itself to taxation in excess of a nominal dollar amount in any such jurisdiction
where it is not then so subject.

            (i)   Cooperate with the selling Holders of Registrable Securities
and the managing underwriter or underwriters, if any, to facilitate the timely
preparation and delivery of certificates representing shares of Registrable
Securities to be sold, which certificates, when such Registrable Securities are
sold pursuant to the Shelf Registration Statement, shall not bear any
restrictive legends and shall be in a form eligible for deposit with The
Depository Trust Company; and enable such shares of Registrable Securities to be
in such denominations and registered in such names as the managing underwriter
or underwriters, if any, or Holders may reasonably request.

            (j)   Use its reasonable best efforts to cause the Registrable
Securities covered by any Shelf Registration Statement to be registered with or
approved by such other governmental agencies or authorities as may be reasonably
necessary to enable the seller or sellers thereof or the underwriter or
underwriters, if any, to consummate the disposition of such Registrable
Securities, except as may be required solely as a consequence of the nature of
such selling Holder's business, in which case the Company will cooperate in all
reasonable respects with the filing of such Registration Statement and the
granting of such approvals.

            (k)   Upon the occurrence of any event contemplated by paragraph
4(c)(ii), 4(c)(iii) or 4(c)(iv) hereof, as promptly as practicable prepare and
(subject to Section 4(a) hereof) file with the SEC, at the sole expense of the
Company, a supplement or post-effective amendment to the Registration Statement
or a supplement to the related Prospectus or any document incorporated or deemed
to be incorporated therein by reference, or file any other required document so
that, as thereafter delivered to the purchasers of the Registrable Securities
being sold thereunder, any such Prospectus will not contain an untrue statement
of a material fact or omit to state a material fact required to be stated
therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading.

            (l)   Prior to the effective date of the first Registration
Statement relating to the Registrable Securities, (i) provide the Trustee with
certificates for the Registrable Securities in a form eligible for deposit with
The Depository Trust Company and (ii) provide required CUSIP numbers for the
Registrable Securities.

            (m)   In connection with any underwritten offering of Registrable
Securities pursuant to a Shelf Registration, enter into an underwriting
agreement as is customary in un-


                                      -10-


<PAGE>


derwritten offerings of securities similar to the Registrable Securities and
take all such other actions as are reasonably requested by the managing
underwriter or underwriters in order to expedite or facilitate the
registration or the disposition of such Registrable Securities and, in such
connection, (i) make such representations and warranties to, and covenants
with, the underwriters with respect to the business of the Company and its
subsidiaries (including any acquired business, properties or entity, if
applicable) and the Registration Statement, Prospectus and documents, if any,
incorporated or deemed to be incorporated by reference therein, in each case,
as are customarily made by issuers to underwriters in underwritten offerings
of securities similar to the Registrable Securities and confirm the same in
writing if and when requested; (ii) obtain the written opinion of counsel to
the Company and written updates thereof in form, scope and substance
reasonably satisfactory to the managing underwriter or underwriters,
addressed to the underwriters covering the matters customarily covered in
opinions requested in underwritten offerings of securities similar to the
Registrable Securities and such other matters as may be reasonably requested
by the managing underwriter or underwriters; and (iii) obtain "cold comfort"
letters and updates thereof in form, scope and substance reasonably
satisfactory to the managing underwriter or underwriters from the independent
certified public accountants of the Company (and, if necessary, any other
independent certified public accountants of any subsidiary of the Company or
of any business acquired by the Company for which financial statements and
financial data are, or are required to be, included or incorporated by
reference in the Registration Statement), addressed to each of the
underwriters, such letters to be in customary form and covering matters of
the type customarily covered in "cold comfort" letters in connection with
underwritten offerings of securities similar to the Registrable Securities
and such other matters as reasonably requested by the managing underwriter or
underwriters as permitted by the Statement on Auditing Standards No. 72. The
above shall be done as and to the extent required by such underwriting
agreement.

            (n)   Make available for inspection by any selling Holder of such
Registrable Securities being sold, any underwriter participating in any such
disposition of Registrable Securities, if any, and any attorney, accountant or
other agent retained by any such selling Holder, or underwriter (collectively,
the "INSPECTORS"), at the offices where normally kept, during reasonable
business hours at such time or times as shall be mutually convenient for the
Company and the Inspectors as a group, all financial and other records,
pertinent corporate documents and instruments of the Company and its
subsidiaries (collectively, the "RECORDS") as shall be reasonably necessary to
enable them to exercise any applicable due diligence responsibilities, and cause
the officers, directors and employees of the Company and its subsidiaries to
supply all information reasonably requested by any such Inspector in connection
with such Registration Statement. Records that the Company determines, in good
faith, to be confidential and any Records that it notifies the Inspectors are
confidential shall not be disclosed or used by any Inspector unless (i) the
disclosure of such Records is necessary to avoid or correct a material
misstatement or material omission in such Registration Statement, (ii) the
release of such Records is ordered pursuant to a subpoena or other order from a
court of competent jurisdiction, (iii) disclosure of such information is made in
a court proceeding or required by law or (iv) the information in such Records
has been made generally available to the


                                      -11-


<PAGE>


public other than through the acts of such Inspector or as a result of a breach
of this Agreement; PROVIDED, HOWEVER, that prior notice shall be provided as
soon as practicable to the Company of the potential disclosure of any
information by such Inspector pursuant to clauses (ii) or (iii) of this sentence
to permit the Company to obtain a protective order (or waive the provisions of
this paragraph (n)) and that such Inspector shall take such actions as are
reasonably necessary to protect the confidentiality of such information (if
practicable) to the extent such action is otherwise not inconsistent with, an
impairment of or in derogation of the rights and interests of any Holder or
Inspector; PROVIDED, FURTHER, that prior to the disclosure to any Inspector of
any Records that the Company determines, in good faith, to be confidential, the
Company may require such Inspector to execute a confidentiality agreement
whereby such Inspector shall agree to the limitations on the disclosure of the
Record to the extent provided above.

            (o)   Provide (i) the Holders of the Registrable Securities to be
included in such Registration Statement and Counsel to the Holders, (ii) the
underwriters (which term, for purposes of this Registration Rights Agreement,
shall include a Person deemed to be an underwriter within the meaning of Section
2(11) of the Securities Act), if any, thereof, (iii) the sales or placement
agent, if any, thereof, and (iv) one counsel for such underwriters or agents,
reasonable opportunity to participate in the preparation of such Registration
Statement, each prospectus included therein or filed with the SEC, and each
amendment or supplement thereto.

            (p)   Comply with all applicable rules and regulations of the SEC
and make generally available to its securityholders earning statements
satisfying the provisions of Section 11(a) of the Securities Act and Rule 158
thereunder (or any similar rule promulgated under the Securities Act) no later
than 45 days after the end of any 12-month period (or 90 days after the end of
any 12-month period if such period is a fiscal year) (i) commencing at the end
of any fiscal quarter in which Registrable Securities are sold to underwriters
in a firm commitment or best efforts underwritten offering and (ii) if not sold
to underwriters in such an offering, commencing on the first day of the first
fiscal quarter of the Company after the effective date of a Registration
Statement, which statements shall cover said 12-month periods.

            (q)   Cooperate with each seller of Registrable Securities covered
by any Registration Statement and each underwriter, if any, participating in the
disposition of such Registrable Securities and their respective counsel in
connection with any filings required to be made with the National Association of
Securities Dealers, Inc. (the "NASD"), including, if the Conduct Rules of the
NASD or any successor thereto as amended from time to time so require, engaging
a "qualified independent underwriter" ("QIU") as contemplated therein and making
Records available to such QIU as though it were a participating underwriter for
the purposes of Section 4(n) and otherwise applying the provisions of this
Agreement to such QIU (including indemnification) as though it were a
participating underwriter.


                                      -12-


<PAGE>


            (r)   Cause the Indenture to be qualified under the TIA not later
than the effective date of the first Registration Statement relating to the
Registrable Securities; and in connection therewith, cooperate with the Trustee
and the Holders of the Registrable Securities to effect such changes to the
Indenture as may be required for the Indenture to be so qualified in accordance
with the terms of the TIA; and execute, and use its reasonable best efforts to
cause the Trustee to execute, all documents as may be required to effect such
changes and all other forms and documents required to be filed with the SEC to
enable the Indenture to be so qualified in a timely manner.

            (s)   Use its reasonable best efforts to take all other steps
necessary or advisable to effect the registration of the Registrable Securities
covered by a Registration Statement contemplated hereby.

            The Company may require each seller of Registrable Securities as to
which any registration is being effected to furnish to the Company such
information regarding such seller and the distribution of such Registrable
Securities as the Company may, from time to time, reasonably request to the
extent necessary or advisable to comply with the Securities Act. The Company may
exclude from such registration the Registrable Securities of any seller if such
seller fails to furnish such information within 20 Business Days after receiving
such request. Each seller as to which any Shelf Registration is being effected
agrees to furnish promptly to the Company all information required to be
disclosed so that the information previously furnished to the Company by such
seller is not materially misleading and does not omit to state any material fact
required to be stated therein or necessary to make the statements therein not
misleading in light of the circumstances under which they were made.

            After the effective date of the Registration Statement, the Company
shall, upon the request of any Holder of Registrable Securities that has not
provided the information pursuant to the foregoing paragraph, send to such
Holder, in customary form, a request for such information. The Company shall not
be required to take any action to name such Holder as a selling securityholder
in the Registration Statement until such Holder has provided such information.
Following its receipt of such information, the Company will reasonably promptly,
and not later than five (5) business days after such receipt, include the
Registrable Securities covered thereby in the Registration Statement and shall
prepare, file and make available to such Holder the Prospectus and any required
prospectus supplement.

            Each Holder of Registrable Securities agrees by acquisition of such
Registrable Securities that, upon actual receipt of any notice from the Company
of the happening of any event of the kind described in Section 4(c)(ii),
4(c)(iii) or 4(c)(iv) hereof, such Holder will forthwith discontinue disposition
of such Registrable Securities covered by such Registration Statement or
Prospectus until such Holder's receipt of the copies of the supplemented or
amended Prospectus contemplated by Section 4(k) hereof, or until it is advised
in writing by the Company that the use of the applicable Prospectus may be
resumed, and has received copies of any amendments or supplements thereto.


                                      -13-


<PAGE>


5.    REGISTRATION EXPENSES

            (a)   All fees and expenses incident to the performance of or
compliance with this Agreement by the Company shall be borne by the Company,
including, without limitation, (i) all registration and filing fees (including,
without limitation, (A) fees with respect to filings required to be made with
the NASD in connection with an underwritten offering and (B) fees and expenses
of compliance with state securities or Blue Sky laws (including, without
limitation, reasonable fees and disbursements of counsel in connection with Blue
Sky qualifications of the Registrable Securities and determination of the
eligibility of the Registrable Securities for investment under the laws of such
jurisdictions as provided in Section 4(h) hereof), (ii) printing expenses,
including, without limitation, expenses of printing certificates for Registrable
Securities in a form eligible for deposit with The Depository Trust Company and
of printing prospectuses if the printing of prospectuses is requested by the
managing underwriter or underwriters, if any, or by the Holders of the majority
in Amount of Registrable Securities included in any Registration Statement,
(iii) messenger, telephone and delivery expenses, (iv) fees and disbursements of
counsel for the Company and reasonable fees and disbursements of special counsel
for the sellers of Registrable Securities (subject to the provisions of Section
5(b) hereof), (v) fees and disbursements of all independent certified public
accountants referred to in Section 4(m)(iii) hereof (including, without
limitation, the expenses of any special audit and "cold comfort" letters
required by or incident to such performance), (vi) Securities Act liability
insurance, if the Company desires such insurance, (vii) fees and expenses of all
other Persons retained by the Company, (viii) internal expenses of the Company
(including, without limitation, all salaries and expenses of officers and
employees of the Company performing legal or accounting duties), (ix) the
expense of any annual audit, (x) the fees and expenses incurred in connection
with the listing of the securities to be registered on any securities exchange,
if applicable, and (xi) the expenses relating to printing, word processing and
distributing all Registration Statements, underwriting agreements, securities
sales agreements and any other documents necessary in order to comply with this
Agreement. Nothwithstanding anything in this Agreement to the contrary, each
Holder shall pay all underwriting discounts and brokerage commissions with
respect to any Registrable Securities sold by it.

            (b)   The Company shall reimburse the Holders of the Registrable
Securities being registered in a Shelf Registration for the reasonable fees and
disbursements of not more than one counsel chosen by the Holders of a majority
in Amount of Registrable Securities to be included in such Registration
Statement ("COUNSEL TO THE HOLDERS").

6.    INDEMNIFICATION

            The Company agrees to indemnify and hold harmless (i) each Initial
Purchaser, (ii) each Holder, (iii) each Person, if any, who controls (within the
meaning of either Section 15 of the Securities Act or Section 20 of the Exchange
Act) any of the foregoing (any of the Persons referred to in this clause (iii)
being hereinafter referred to as a "controlling person"),


                                      -14-


<PAGE>


(iv) the respective officers, directors, partners, employees, representatives
and agents of the Initial Purchasers, the Holders (including predecessor
Holders) or any controlling person (any person referred to in clause (i), (ii),
(iii) or (iv) may hereinafter be referred to as an "INDEMNIFIED HOLDER"), from
and against any and all losses, claims, damages, liabilities and judgments
(including, without limitation, reasonable legal fees and other expenses
incurred in connection with any suit, action or proceeding or any claim
asserted) caused by any untrue statement or alleged untrue statement of a
material fact contained in any Registration Statement or Prospectus, or any
amendment or supplement thereto or any related preliminary prospectus, or caused
by any omission or alleged omission to state therein a material fact required to
be stated therein or necessary to make the statements therein not misleading,
except insofar as such losses, claims, damages or liabilities are caused by any
untrue statement or omission or alleged untrue statement or omission made in
reliance upon and in conformity with information relating to any Holder
furnished to the Company in writing by such Holder expressly for use in therein;
PROVIDED, HOWEVER, that the Company shall not be liable to any Indemnified
Holder under the indemnity agreement of this paragraph with respect to any
preliminary prospectus to the extent that any such loss, claim, damage,
liability, judgment or expense of such Indemnified Holder results from the fact
that such Indemnified Holder sold Registrable Securities under a Registration
Statement to a Person as to whom it shall be established that there was not sent
or given, at or prior to the written confirmation of such sale, a copy of the
Prospectus (or of the preliminary prospectus as then amended or supplemented if
the Company shall have furnished such Indemnified Holder with such amendment or
supplement thereto on a timely basis), in any case where such delivery is
required by applicable law and the loss, claim, damage, liability or expense of
such Indemnified Holder results from an untrue statement or omission of a
material fact contained in the preliminary prospectus which was corrected in the
Prospectus (or in the preliminary prospectus as then amended or supplemented if
the Company shall have furnished such Indemnified Holder with such amendment or
supplement thereto, as the case may be, on a timely basis). The Company shall
notify Indemnified Holder promptly of the institution, threat or assertion of
any claim, proceeding (including any governmental investigation) or litigation
in connection with the matters addressed by this Agreement which involves the
Company or such Indemnified Holder.

            Each Holder agrees, severally and not jointly, to indemnify and hold
harmless the Company, its directors, officers and each Person who controls the
Company within the meaning of either Section 15 of the Securities Act or Section
20 of the Exchange Act to the same extent as the foregoing indemnity from the
Company to each Holder, but only with reference to such losses, claims, damages
or liabilities which are caused by any untrue statement or omission or alleged
untrue statement or omission made in reliance upon and in conformity with
information relating to a Holder furnished to the Company in writing by such
Holder expressly for use in any Registration Statement or Prospectus, or any
amendment or supplement thereto or any related preliminary prospectus.

            If any suit, action, proceeding (including any governmental or
regulatory investigation), claim or demand shall be brought or asserted against
any Person in respect of


                                      -15-


<PAGE>


which indemnity may be sought pursuant to either of the two preceding
paragraphs, such Person (the "INDEMNIFIED PERSON") shall promptly notify the
Person or Persons against whom such indemnity may be sought (each an
"INDEMNIFYING PERSON") in writing, and such Indemnifying Person, upon request of
the Indemnified Person, shall retain counsel reasonably satisfactory to the
Indemnified Person to represent the Indemnified Person and any others entitled
to indemnification pursuant to this Section 6 that the Indemnifying Person may
designate in such proceeding and shall pay the fees and expenses of such counsel
related to such proceeding. In any such proceeding, any Indemnified Person shall
have the right to retain its own counsel, but the fees and expenses of such
counsel shall be at the expense of such Indemnified Person unless (i) such
Indemnifying Person and the Indemnified Person shall have mutually agreed to the
contrary, (ii) such Indemnifying Person has failed within a reasonable time to
retain counsel reasonably satisfactory to such Indemnified Person or (iii) the
named parties in any such proceeding (including any impleaded parties) include
an Indemnifying Person and an Indemnified Person and representation of both
parties by the same counsel would be inappropriate due to actual or potential
differing interests between them. It is understood that an Indemnifying Person
shall not, in connection with any proceeding or related proceedings in the same
jurisdiction, be liable for the fees and expenses of more than one separate firm
(in addition to any local counsel) for all Indemnified Persons, and that all
such fees and expenses shall be reimbursed as they are incurred. Any such
separate firm for the Indemnified Holders shall be designated in writing by the
Holders of the majority in Amount of Registrable Securities, and any such
separate firm for the Company, its directors, respective officers and such
control Persons of the Company shall be designated in writing by the Company.
The Indemnifying Person shall not be liable for any settlement of any proceeding
effected without its written consent, but if settled with such consent or if
there be a final judgment for the plaintiff, such Indemnifying Person agrees to
indemnify any Indemnified Person from and against any loss or liability by
reason of such settlement or judgment. No Indemnifying Person shall, without the
prior written consent of the Indemnified Person, effect any settlement of any
pending or threatened proceeding in respect of which any Indemnified Person is
or could have been a party and indemnity could have been sought hereunder by
such Indemnified Person, unless such settlement includes an unconditional
release of such Indemnified Person from all liability on claims that are the
subject matter of such proceeding.

            If the indemnification provided for in the first and second
paragraphs of this Section 6 is unavailable to an Indemnified Person or
insufficient in respect of any losses, claims, damages or liabilities referred
to therein, then each Indemnifying Person under such paragraph, in lieu of
indemnifying such Indemnified Person thereunder, shall contribute to the amount
paid or payable by such Indemnified Person as a result of such losses, claims,
damages or liabilities (i) in such proportion as is appropriate to reflect the
relative benefits received by the Indemnifying Person on the one hand and the
Indemnified Person on the other hand pursuant to the Purchase Agreement or from
the offering of the Registrable Securities pursuant to any Shelf Registration or
(ii) if the allocation provided by clause (i) above is not permitted by
applicable law, in such proportion as is appropriate to reflect not only the
relative benefits referred to in clause (i) above but also the relative fault of
the Indemnifying Person on


                                      -16-


<PAGE>


the one hand and the Indemnified Person on the other in connection with the
statements or omissions that resulted in such losses, claims, damages or
liabilities, as well as any other relevant equitable considerations. The
relative benefits received by the Company on the one hand and any Indemnified
Holder on the other shall be deemed to be in the same proportion as the total
net proceeds from the initial offering and sale of Convertible Notes (before
deducting expenses) received by the Company bear to the total net proceeds
received by such Indemnified Holder from sales of Registrable Securities giving
rise to such obligations. The relative fault of the parties shall be determined
by reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission or alleged omission to state a
material fact relates to information supplied by the Company or such Indemnified
Holder and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission.

            Each of the Company and the Initial Purchasers agrees that it would
not be just and equitable if contribution pursuant to this Section 6 were
determined by PRO RATA allocation or by any other method of allocation that does
not take account of the equitable considerations referred to in the immediately
preceding paragraph. The amount paid or payable by an Indemnified Person as a
result of the losses, claims, damages and liabilities referred to in the
immediately preceding paragraph shall be deemed to include, subject to the
limitations set forth above, any legal or other expenses incurred by such
Indemnified Person in connection with investigating or defending any such action
or claim. Notwithstanding the provisions of this Section 6, in no event shall
any Holder be required to contribute any amount in excess of the amount by which
the net proceeds received by such Holder from the sale of the Registrable
Securities pursuant to a Shelf Registration Statement exceeds the amount of
damages which such Holder would have otherwise been required to pay by reason of
such untrue or alleged untrue statement or omission or alleged omission. No
Person guilty of fraudulent misrepresentation (within the meaning of Section
11(F) of the Securities Act) shall be entitled to contribution from any Person
who was not guilty of such fraudulent misrepresentation.

            The remedies provided for in this Section 6 are not exclusive and
shall not limit any rights or remedies that may otherwise be available to any
indemnified party at law or in equity.

            The indemnity and contribution agreements contained in this Section
6 shall remain operative and in full force and effect regardless of (i) any
termination of this Agreement, (ii) any investigation made by or on behalf of
any Holder or any Person controlling any Holder or by or on behalf of the
Company, its officers or directors or any other Person controlling any of the
Company and (iii) acceptance of and payment for any of the Registrable
Securities.


                                      -17-


<PAGE>


7.    RULES 144 AND 144A.
      ------------------

            The Company covenants that it will file the reports required to be
filed by it under the Securities Act and the Exchange Act and the rules and
regulations adopted by the SEC thereunder in a timely manner in accordance with
the requirements of the Securities Act and the Exchange Act and, for so long as
any Registrable Securities remain outstanding, if at any time the Company is not
required to file such reports, it will, upon the request of any Holder or
beneficial owner of Registrable Securities, make available such information
necessary to permit sales pursuant to Rule 144A under the Securities Act. The
Company further covenants that, for so long as any Registrable Securities remain
outstanding, it will use its reasonable best efforts to take such further action
as any Holder of Registrable Securities may reasonably request, all to the
extent required from time to time to enable such holder to sell Registrable
Securities without registration under the Securities Act within the limitation
of the exemptions provided by (a) Rule 144(k) and Rule 144A under the Securities
Act, as such rules may be amended from time to time, or (b) any similar rule or
regulation hereafter adopted by the SEC. Notwithstanding the foregoing, nothing
in this Section 7 shall be deemed to require the Company to register any of its
securities pursuant to the Exchange Act.

8.    UNDERWRITTEN REGISTRATIONS.
      --------------------------

            If any of the Registrable Securities covered by any Shelf
Registration are to be sold in an underwritten offering, the investment banker
or investment bankers and manager or managers that will manage the offering will
be selected by the Holders of the majority in Amount of Registrable Securities
to be included in such offering and will be reasonably acceptable to the
Company.

            No Holder of Registrable Securities may participate in any
underwritten registration hereunder unless such Holder (a) agrees to sell such
Holder's Registrable Securities on the basis provided in any underwriting
arrangements approved by the Persons entitled hereunder to approve such
arrangements and (b) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements.

9.    MISCELLANEOUS
      -------------

            (a)   NO INCONSISTENT AGREEMENTS. The Company has not, as of the
date hereof, and the Company shall not, after the date of this Agreement, enter
into any agreement with respect to any of its securities that is inconsistent
with the rights granted to the Holders of Registrable Securities in this
Agreement or otherwise conflicts with the provisions hereof. The Company has not
entered and will not enter into any agreement with respect to any of its
securities that will grant to any Person piggyback registration rights with
respect to a Registration Statement, except to the extent any existing right has
heretofore been waived.


                                      -18-


<PAGE>


            (b)   ADJUSTMENTS AFFECTING REGISTRABLE SECURITIES. The Company
shall not, directly or indirectly, take any action with respect to the
Registrable Securities as a class that would adversely affect the ability of the
Holders of Registrable Securities to include such Registrable Securities in a
registration undertaken pursuant to this Agreement.

            (c)   AMENDMENTS AND WAIVERS. The provisions of this Agreement may
not be amended, modified or supplemented, and waivers or consents to departures
from the provisions hereof may not be given, otherwise than with the prior
written consent of the Company and the Holders of not less than the majority in
Amount of Registrable Securities; PROVIDED, HOWEVER, that Section 6 and this
Section 9(c) may not be amended, modified or supplemented without the prior
written consent of the Company and each Holder (including, in the case of an
amendment, modification or supplement of Section 6, any Person who was a Holder
of Registrable Securities disposed of pursuant to any Registration Statement).
Notwithstanding the foregoing, a waiver or consent to depart from the provisions
hereof with respect to a matter that relates exclusively to the rights of
Holders of Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect, impair,
limit or compromise the rights of other Holders of Registrable Securities may be
given by Holders of at least a majority in Amount of the Registrable Securities
being sold by such Holders pursuant to such Registration Statement.

            (d)   NOTICES. All notices and other communications (including
without limitation any notices or other communications to the Trustee) provided
for or permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, next-day air courier or facsimile:

                  (1)   if to a Holder of the Registrable Securities, at the
            most current address of such Holder set forth on the records of the
            registrar under the Indenture, in the case of Holders of Convertible
            Notes, and the stock ledger of the Company, in the case of Holders
            of common stock of the Company.

                  (2)   if to the Initial Purchasers:

                  J.P. MORGAN SECURITIES INC.
                  CHASE SECURITIES INC.
                  LEHMAN BROTHERS INC.
                  MORGAN STANLEY & CO. INCORPORATED
                  c/o J.P. Morgan Securities Inc.
                  60 Wall Street
                  New York, New York 10260
                  Attention:        Syndicate Department



                                   -19
<PAGE>


            with copies to:

                  Cahill Gordon & Reindel
                  80 Pine Street
                  New York, New York 10005
                  Facsimile No.:  (212) 269-5420
                  Attention:        Gerald Tanenbaum, Esq.

                  (3)   if to the Company, at the addresses as follows:

                  Gilead Sciences, Inc.
                  333 Lakeside Drive
                  Foster City, California 94404
                  Attention:        Gregg H. Alton, Esq., General Counsel

            with copies to:

                  Cooley Godward LLP
                  5 Palo Alto Square
                  Palo Alto, California 94360
                  Facsimile No.:  (650) 849-7400
                  Attention:  Laura A. Berezin, Esq.

                  All such notices and communications shall be deemed to have
been duly given: when delivered by hand, if personally delivered; five Business
Days after being deposited in the mail, postage prepaid, if mailed; one Business
Day after being timely delivered to a next-day air courier; and when receipt is
acknowledged by the addressee, if sent by facsimile.

                  (e)   SUCCESSORS AND ASSIGNS. This Agreement shall inure to
the benefit of and be binding upon the successors and assigns of each of the
parties hereto, including the Holders; PROVIDED, HOWEVER, that this Agreement
shall not inure to the benefit of or be binding upon a successor or assign of a
Holder unless and except to the extent such successor or assign holds
Registrable Securities.

                  (f)   COUNTERPARTS. This Agreement may be executed in any
number of counterparts and by the parties hereto in separate counterparts, each
of which when so executed shall be deemed to be an original and all of which
taken together shall constitute one and the same agreement.

                  (g)   HEADINGS. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

                  (h)   GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW


                                      -20-

<PAGE>


YORK, AS APPLIED TO CONTRACTS MADE AND PERFORMED WHOLLY WITHIN THE STATE OF NEW
YORK, WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW. EACH OF THE PARTIES
HERETO AGREES TO SUBMIT TO THE JURISDICTION OF THE FEDERAL AND NEW YORK STATE
COURTS SITTING IN MANHATTAN, NEW YORK CITY, THE STATE OF NEW YORK, IN ANY ACTION
OR PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT.

                  (i)   SEVERABILITY. If any term, provision, covenant or
restriction of this Agreement is held by a court of competent jurisdiction to be
invalid, illegal, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions set forth herein shall remain in full force and
effect and shall in no way be affected, impaired or invalidated, and the parties
hereto shall use their best efforts to find and employ an alternative means to
achieve the same or substantially the same result as that contemplated by such
term, provision, covenant or restriction. It is hereby stipulated and declared
to be the intention of the parties that they would have executed the remaining
terms, provisions, covenants and restrictions without including any of such that
may be hereafter declared invalid, illegal, void or unenforceable.

                  (j)   SECURITIES HELD BY THE COMPANY OR ITS AFFILIATES.
Whenever the consent or approval of Holders of a specified percentage in Amount
of Registrable Securities is required hereunder, Registrable Securities held by
the Company or its affiliates (as such term is defined in Rule 405 under the
Securities Act) shall not be counted in determining whether such consent or
approval was given by the Holders of such required percentage.

                  (k)   THIRD PARTY BENEFICIARIES. Holders of Registrable
Securities are intended third party beneficiaries of this Agreement and this
Agreement may be enforced by such Persons.

                  (l)   ENTIRE AGREEMENT. This Agreement, together with the
Purchase Agreement and the Indenture, is intended by the parties as a final and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter contained herein and therein and any and all prior
oral or written agreements, representations, or warranties, contracts,
understandings, correspondence, conversations and memoranda between the Initial
Purchasers on the one hand and the Company on the other, or between or among any
agents, representatives, parents, subsidiaries, affiliates, predecessors in
interest or successors in interest with respect to the subject matter hereof and
thereof are merged herein and replaced hereby.


                                      -21-


<PAGE>




            IN WITNESS WHEREOF, the parties have executed this Agreement as of
the date first written above.

                                        GILEAD SCIENCES, INC.


                                        By: /s/ John C. Martin
                                           ------------------------------
                                           Name: John C. Martin
                                           Title: President And Chief Executive
                                                  Officer


                                        J.P. MORGAN SECURITIES INC.
                                        CHASE SECURITIES INC.
                                        LEHMAN BROTHERS INC.
                                        MORGAN STANLEY & CO. INCORPORATED


                                        By: J.P. MORGAN SECURITIES INC.



                                           By: /s/ J.P. Morgan Securities Inc.
                                              --------------------------------
                                              Name:
                                              Title:






                                      -22-