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                                                                    EXHIBIT 10.1

                             COR Therapeutics, Inc.

                4.50% Convertible Senior Notes due June 15, 2006


                                ________________


                               Purchase Agreement
                               ------------------

                                                     June 6, 2001

Goldman, Sachs & Co.,
Robertson Stephens, Inc.
Credit Suisse First Boston Corporation
CIBC World Markets Corp.
Needham & Company, Inc.
c/o Goldman, Sachs & Co.,
85 Broad Street,
New York, New York 10004.

Ladies and Gentlemen:

     COR Therapeutics, Inc., a Delaware corporation (the "Company"), proposes,
subject to the terms and conditions stated herein, to issue and sell to the
Purchasers named in Schedule I hereto (the "Purchasers") an aggregate of
$250,000,000 principal amount of the Convertible Senior Notes specified above,
convertible into common stock, par value $0.001 ("Stock"), of the Company (the
"Firm Securities") and, at the election of the Purchasers, up to an aggregate of
$50,000,000 additional aggregate principal amount of such Notes (the "Optional
Securities").  The Firm Securities and the Optional Securities which the
Purchasers elect to purchase pursuant to Section 2 hereof are herein
collectively called the "Securities".

     The Purchasers and other holders (including subsequent transferees) of
Securities in registered form without coupons will be entitled to the benefits
of the registration rights agreement, to be dated as of the First Time of
Delivery (as defined in Section 4) (the "Registration Rights Agreement"), by and
among the Company and the Purchasers, in the form attached hereto as Exhibit A.
Pursuant to the Registration Rights Agreement, the Company will agree to file
with the Securities and Exchange Commission (the "Commission") under the
circumstances set forth therein a shelf registration statement (the
"Registration Statement") pursuant to Rule 415 under the Securities Act of 1933,
as amended (the "Securities Act"), relating to the resale of the Securities and
shares of Stock initially issuable upon conversion of the Securities by holders
thereof, and to use its reasonable efforts to cause such shelf registration
statement to be declared effective as provided therein.
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     1.  The Company represents and warrants to, and agrees with, each of the
Purchasers that:

         (a) (i) A preliminary offering circular, dated June 1, 2001 (the
     "Preliminary Offering Circular") and an offering circular, dated June 6,
     2001 (the "Offering Circular") have been prepared in connection with the
     offering of the Securities and shares of the Stock issuable upon conversion
     thereof. Any reference to the Preliminary Offering Circular or the Offering
     Circular shall be deemed to refer to and include the documents incorporated
     by reference therein including the Company's most recent Annual Report on
     Form 10-K for the fiscal year ended December 31, 2000 and Quarterly Report
     on Form 10-Q for the quarter ended March 31, 2001, which are attached to
     and made a part of the Preliminary Offering Circular and the Offering
     Circular, and all subsequent documents filed with the United States
     Securities and Exchange Commission (the "Commission") pursuant to Section
     13(a), 13(c), 14 or 15(d) of the United States Securities Exchange Act of
     1934, as amended (the "Exchange Act"), on or prior to the date of the
     Preliminary Offering Circular or the Offering Circular, as the case may be,
     and any reference to the Preliminary Offering Circular or the Offering
     Circular, as the case may be, as amended or supplemented, as of any
     specified date, shall be deemed to include (i) any documents filed with the
     Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange
     Act after the date of the Preliminary Offering Circular or the Offering
     Circular, as the case may be, and prior to such specified date and (ii) any
     Additional Issuer Information (as defined in Section 5(f)) furnished by the
     Company prior to the completion of the distribution of the Securities; and
     all documents filed under the Exchange Act and so deemed to be included in
     the Preliminary Offering Circular or the Offering Circular, as the case may
     be, or any amendment or supplement thereto are hereinafter called the
     "Exchange Act Reports". The Preliminary Offering Circular or the Offering
     Circular and any amendments or supplements thereto did not and will not, as
     of their respective dates, contain an untrue statement of a material fact
     or omit to state a material fact necessary in order to make the statements
     therein, in the light of the circumstances under which they were made, not
     misleading; provided, however, that this representation and warranty shall
     not apply to any statements or omissions made in reliance upon and in
     conformity with information furnished in writing to the Company by a
     Purchaser through Goldman, Sachs & Co. expressly for use therein;

             (ii)  The Exchange Act Reports, when they were or are filed with
     the Commission, conformed or will conform in all material respects to the
     applicable requirements of the Exchange Act and the applicable rules and
     regulations of the Commission thereunder, and the Exchange Act Reports did
     not and will not, as of their respective dates, contain an untrue statement
     of a material fact or omit to state a material fact necessary in order to
     make the statements therein, in the light of the circumstances under which
     they were made, not misleading; and

             (iii)  The information provided by the Company pursuant to Section
     5(f) will not, at the date thereof, contain any untrue statement of a
     material fact or omit to state any material fact necessary in order to make
     the statements therein, in the light of the circumstances under which they
     were made, not misleading;

         (b) The Company has not sustained since the date of the latest audited
     financial statements included in the Offering Circular any material loss or
     interference with its business

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     from fire, explosion, flood or other calamity, whether or not covered by
     insurance, or from any labor dispute or court or governmental action, order
     or decree, otherwise than as set forth or contemplated in the Offering
     Circular; and, since the respective dates as of which information is given
     in the Offering Circular, there has not been any decrease in the capital
     stock or increase in long-term debt in excess of $1 million of the Company
     or any material adverse change, or any development involving a prospective
     material adverse change, in or affecting the general affairs, management,
     financial position, stockholders' equity or results of operations of the
     Company, otherwise than as set forth or contemplated in the Offering
     Circular;

         (c) The Company has good and marketable title to all material personal
     property owned by it, free and clear of all liens, encumbrances and defects
     except such as are described in the Offering Circular or such as do not
     interfere with the use made and proposed to be made of such property by the
     Company; and any real property and buildings held under lease by the
     Company are held by it under valid, subsisting and enforceable leases with
     such exceptions as are not material and do not interfere with the use made
     and proposed to be made of such property and buildings by the Company; the
     Company owns no real property;

         (d) The Company has been duly incorporated and is validly existing as a
     corporation in good standing under the laws of the State of Delaware, with
     full corporate power and authority to own (or lease) its properties and
     conduct its business as described in the Offering Circular, and has been
     duly qualified as a foreign corporation for the transaction of business and
     is in good standing under the laws of each other jurisdiction in which it
     owns or leases properties or conducts any business so as to require such
     qualification, or is subject to no material liability or disability by
     reason of the failure to be so qualified in any such jurisdiction; the
     Company has no subsidiaries;

         (e) The Company has an authorized capitalization as set forth in the
     Offering Circular, and all of the issued shares of capital stock of the
     Company have been duly and validly authorized and issued and are fully paid
     and non-assessable; the shares of Stock initially issuable upon conversion
     of the Securities have been duly and validly authorized and reserved for
     issuance and, when issued and delivered in accordance with the provisions
     of the Securities and the Indenture (as defined in Section I(f)), will be
     duly and validly issued, fully paid and non-assessable and will conform to
     the description of the Stock contained in the Offering Circular;

         (f) The Securities have been duly authorized and, when issued and
     delivered pursuant to this Agreement, will have been duly executed,
     authenticated, issued and delivered and will constitute valid and legally
     binding obligations of the Company enforceable in accordance with their
     terms and entitled to the benefits provided by the indenture to be dated as
     of June 11, 2001  (the "Indenture") between the Company and Firstar Bank,
     N.A., as Trustee (the "Trustee"), under which they are to be issued, which
     will be substantially in the form previously delivered to you; the
     Indenture has been duly authorized and, when executed and delivered by the
     Company and the Trustee, the Indenture will constitute a valid and legally
     binding instrument, enforceable in accordance with its terms, subject, as
     to enforcement, to bankruptcy, insolvency, reorganization and other laws of
     general applicability relating to or affecting creditors' rights and to
     general equity principles; and the Securities and the Indenture

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     will conform to the descriptions thereof in the Offering Circular and will
     be in substantially the form previously delivered to you;

         (g) None of the transactions contemplated by this Agreement (including,
     without limitation, the use of the proceeds from the sale of the
     Securities) will violate or result in a violation of Section 7 of the
     Exchange Act, or any regulation promulgated thereunder, including, without
     limitation, Regulations G, T, U, and X of the Board of Governors of the
     Federal Reserve System;

         (h) Prior to the date hereof, neither the Company nor any of its
     affiliates has taken any action which is designed to or which has
     constituted or which might reasonably have been expected to cause or result
     in stabilization or manipulation of the price of any security of the
     Company in connection with the offering of the Securities;

         (i) The issue and sale of the Securities and the compliance by the
     Company with all of the provisions of the Securities, the Registration
     Rights Agreement, the Indenture and this Agreement and the consummation of
     the transactions herein and therein contemplated will not conflict with or
     result in a breach or violation of any of the terms or provisions of, or
     constitute a default under, any indenture, mortgage, deed of trust, loan
     agreement or other material agreement or instrument to which the Company is
     a party or by which the Company is bound or to which any of the property or
     assets of the Company is subject, nor will such action result in any
     violation of the provisions of the Certificate of Incorporation or By-laws
     of the Company or, except as to any violations which would not have a
     Material Adverse Effect (as defined below), any statute or any order, rule
     or regulation of any court or governmental agency or body having
     jurisdiction over the Company or any of its properties; and no consent,
     approval, authorization, order, registration or qualification of or with
     any such court or governmental agency or body is required for the issue and
     sale of the Securities or the consummation by the Company of the
     transactions contemplated by this Agreement, the Registration Rights
     Agreement or the Indenture, except (i) as required pursuant to the
     Registration Rights Agreement, (ii) for the approval of the Stock issuable
     upon conversion of the Securities for quotation on the Nasdaq National
     Market and (iii) such consents, approvals, authorizations, registrations or
     qualifications as may be required under state securities or Blue Sky laws
     in connection with the purchase and distribution of the Securities by the
     Purchasers;

         (j) The Company is not in violation of its Certificate of Incorporation
     or By-laws or in default in the performance or observance of any material
     obligation, covenant or condition contained in any indenture, mortgage,
     deed of trust, loan agreement, material lease or other material agreement
     or instrument to which it is a party or by which it or any of its
     properties may be bound;

         (k) The statements set forth in the Offering Circular under the caption
     "Description of the Notes" and "Description of Capital Stock", insofar as
     they purport to constitute a summary of the terms of the Securities and the
     Stock, and under the caption "Underwriting", insofar as they purport to
     describe the provisions of the documents referred to therein, accurately
     and fairly present in all material respects such matters and documents (to
     the same extent as would be required if the Offering Circular were a
     prospectus included in a Registration Statement of the Company on Form S-1
     under the Securities Act);

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         (l) Other than as set forth in the Offering Circular, there are no
     legal or governmental proceedings pending to which the Company is a party
     or of which any property of the Company is the subject which, if determined
     adversely to the Company, would individually or in the aggregate have a
     material adverse effect on the business, prospects, financial condition or
     results of operations of the Company or on the ability of the Company to
     consummate the transactions contemplated herein (a "Material Adverse
     Effect"); and, to the Company's knowledge, no such proceedings are
     threatened by governmental authorities or by others;

         (m) When the Securities are issued and delivered pursuant to this
     Agreement, the Securities will not be of the same class (within the meaning
     of Rule 144A under the Securities Act) as securities which are listed on a
     national securities exchange registered under Section 6 of the Exchange Act
     or quoted in a U.S. automated inter-dealer quotation system;

         (n) The Company is subject to Section 13 or 15(d) of the Exchange Act;

         (o) The Company is not, and after giving effect to the offering and
     sale of the Securities, will not be, an "investment company", as such term
     is defined in the United States Investment Company Act of 1940, as amended
     (the "Investment Company Act");

         (p) Neither the Company, nor any person acting on its behalf has
     offered or sold the Securities by means of any general solicitation or
     general advertising within the meaning of Rule 502(c) under the Securities
     Act (except that no representation or warranty is made with respect to the
     Purchasers or any persons acting on their behalf);

         (q) Within the preceding six months, neither the Company nor any other
     person acting on behalf of the Company has offered or sold to any person
     any Securities, or any securities of the same or a similar class as the
     Securities, other than Securities offered or sold to the Purchasers
     hereunder.  The Company will take reasonable precautions designed to insure
     that any offer or sale, direct or indirect, in the United States or to any
     U.S. person (as defined in Rule 902 under the Securities Act) of any
     Securities or any substantially similar security issued by the Company,
     within six months subsequent to the date on which the distribution of the
     Securities has been completed (as notified to the Company by Goldman, Sachs
     & Co.), is made under restrictions and other circumstances reasonably
     designed not to affect the status of the offer and sale of the Securities
     in the United States and to U.S. persons contemplated by this Agreement as
     transactions exempt from the registration provisions of the Securities Act
     (except that no representation or warranty is made with respect to the
     Purchasers or any persons acting on their behalf);

         (r) It is not necessary in connection with the offer, sale and delivery
     of the Securities to the Purchasers, or in connection with the initial
     resale of the Securities by the Purchasers in accordance with this
     Agreement, to register the Securities under the Securities Act or to
     qualify an indenture under the Trust Indenture Act of 1939, as amended (the
     "Trust Indenture Act");

         (s) The Securities have been designated PORTAL eligible securities in
     accordance with the rules and regulations of the National Association of
     Securities Dealers, Inc.;

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         (t) The Company has all requisite corporate power to enter into this
     Agreement and the Registration Rights Agreement.  This Agreement has been
     and, as of the First Time of Delivery (as defined below), the Registration
     Rights Agreement will have been, duly authorized, executed and delivered by
     the Company and upon such execution by the Company (assuming the due
     authorization, execution and delivery of such agreements by the other
     parties thereto) this Agreement and the Registration Rights Agreement will
     constitute the valid and binding obligations of the Company enforceable
     against the Company in accordance with the terms hereof or thereof,
     subject, as to enforcement, to bankruptcy, insolvency, reorganization and
     other laws of general applicability relating to or affecting creditors'
     rights and to general equity principles, and except as the enforcement of
     indemnification and contribution provisions hereof and thereof may be
     limited by applicable law;

         (u)  Except as disclosed in the Offering Circular, there are no persons
     with registration rights or other similar rights to have any securities of
     the Company (other than the Securities and the shares of Stock issuable
     upon conversion thereof) registered under any Securities Act registration
     statement;

         (v) None of the holders of outstanding shares of capital stock of the
     Company and no other person has or will have any preemptive or other rights
     to purchase, subscribe for or otherwise acquire (i) the shares of Stock to
     be issued upon conversion of the Securities or any rights to such shares
     (other than those granted by the holders of the Securities) or (ii) as a
     result of or in connection with the transactions contemplated by the
     Indenture, this Agreement or the Registration Rights Agreement, any other
     capital stock of the Company or rights thereto;

         (w) The Company's directors and executive officers, in each case as
     listed on Exhibit B-1, have entered into a written agreement with the
     Company in the form of Exhibit B hereto (each such agreement, a "Lock-up
     Agreement"), and executed originals of each Lock-up Agreement have been
     delivered to you;

         (x) To the Company's knowledge, Ernst & Young LLP, who have certified
     certain financial statements of the Company, are independent public
     accountants as required by the Act and the rules and regulations of the
     Commission thereunder.

         (y) (i) The Company owns, or possesses adequate rights to use, all
     material trademarks, service marks, trade names, trademark registrations,
     service mark registrations, domain names and copyrights necessary for the
     conduct of its business and, except as set forth in the Offering Circular,
     has not received any notice of any claim of conflict with any such rights
     of others except as would not have a Material Adverse Effect; and (ii) to
     the Company's knowledge, the Company has not infringed and is not
     infringing any trademarks, service marks, trade names, trademark
     registrations, service mark registrations, domain names or copyrights,
     which infringement could reasonably be expected to result in any Material
     Adverse Effect;

         (z) (i) The Company owns or possesses adequate rights to use, all
     material patents necessary for the conduct of its business; (ii) to the
     Company's knowledge, no valid United States patent is or would be infringed
     by the activities of the Company, except as would not

                                       6
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     have a Material Adverse Effect; (iii) except as set forth in the Offering
     Circular, there are no actions, suits or judicial proceedings pending
     relating to patents or proprietary information to which the Company is a
     party or of which any property of the Company is subject, and, to the
     knowledge of the Company, no actions, suits or judicial proceedings are
     threatened in writing by governmental authorities or others, in each case
     except as would not result in any Material Adverse Effect; and (iv) except
     as set forth in the Offering Circular or as would not result in any
     Material Adverse Effect, the Company has not been notified in writing that
     the Company is infringing or otherwise violating the patents or other
     intellectual property of others and is not aware of any rights of third
     parties to any of the Company's material patent applications, license
     patents or licenses that in any case could affect materially the use
     thereof by the Company;

         (aa) The Company carries, or is covered by, insurance as is customary
     for companies similarly situated and engaged in similar businesses in
     similar industries;

         (bb) No labor disturbance by the employees of the Company exists or, to
     the knowledge of the Company, is imminent which might be expected to have a
     Material Adverse Effect; and

         (cc) The Company is in compliance with all rules, laws and regulations
     relating to the use, treatment, storage and disposal of toxic substances
     and protection of health or the environment ("Environmental Laws") which
     are applicable to its business except for failure to comply which would not
     have a Material Adverse Effect.  The Company has received no written notice
     from any governmental authority or third party of an asserted claim under
     Environmental Laws, which claim is required to be disclosed in the Offering
     Circular.  To its knowledge, the Company has not conducted any activity
     which would require it to make material capital expenditures to comply with
     Environmental Laws.  No property which is owned, leased or occupied by the
     Company has been designated a Superfund site pursuant to the Comprehensive
     Response, Compensation, and Liability Act of 1980, as amended (42 U.S.C.
     ss. 9601, et seq.), or otherwise designated as a contaminated site (which
     designation as a contaminated site would be expected to be material to the
     Company) under applicable state or local law.

     2.  Subject to the terms and conditions herein set forth, (a) the Company
agrees to issue and sell to each of the Purchasers, and each of the Purchasers
agrees, severally and not jointly, to purchase from the Company, at a purchase
price of 96.75% of the principal amount thereof, plus accrued interest, if any,
from June 11, 2001 to the First Time of Delivery hereunder, the principal amount
of Firm Securities set forth opposite the name of such Purchaser in Schedule I
hereto, and (b) in the event and to the extent that you shall exercise the
election to purchase Optional Securities as provided below, the Company agrees
to issue and sell to each of the Purchasers, and each of the Purchasers agrees,
severally and not jointly, to purchase from the Company, at the same purchase
price set forth in clause (a) of this Section 2, the aggregate principal amount
of the Optional Securities as to which such election shall have been exercised
(to be adjusted by you so as to eliminate denominations of less than U.S.$1,000)
determined by multiplying such aggregate principal amount of Optional Securities
by a fraction, the numerator of which is the maximum aggregate principal amount
of Optional Securities which such Purchaser is entitled to purchase as set forth
opposite the name of such Purchaser in Schedule I hereto and the denominator of
which is the maximum aggregate principal amount of Optional Securities which all
of the Purchasers are entitled to purchase hereunder.

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     The Company hereby grants to the Purchasers the right to purchase at their
election up to $50,000,000 aggregate principal amount of Optional Securities, at
the purchase price set forth in clause (a) of the first paragraph of this
Section 2, for the sole purpose of covering sales of Securities in excess of the
number of Firm Securities. Any such election to purchase Optional Securities may
be exercised by written notice from you to the Company, given within a period of
30 calendar days after the date of this Agreement, setting forth the aggregate
principal amount of Optional Securities to be purchased and the date on which
such Optional Securities are to be delivered, as determined by you but in no
event earlier than the First Time of Delivery or, unless you and the Company
otherwise agree in writing, earlier than two or later than ten business days
after the date of such notice.

     3.  Upon the authorization by you of the release of the Securities, the
several Purchasers propose to offer the Securities for sale upon the terms and
conditions set forth in this Agreement and the Offering Circular and each
Purchaser hereby represents and warrants to, and agrees with the Company that:

     (a) It will offer and sell the Securities only to: persons who it
reasonably believes are "qualified institutional buyers" ("QIBs") within the
meaning of Rule 144A under the Securities Act in transactions meeting the
requirements of Rule 144A;

     (b) It is an institution that is an "accredited investor" within the
meaning of Rule 501 under the Securities Act; and

     (c) It will not offer or sell the Securities by any form of general
solicitation or general advertising, including but not limited to the methods
described in Rule 502(c) under the Securities Act.

     4.  (a) The Securities will be represented by one or more definitive global
Securities in book-entry form which will be deposited by or on behalf of the
Company with The Depository Trust Company ("DTC") or its designated custodian.
The Company will deliver the Securities to the Purchasers, against payment by
the Purchasers of the purchase price therefor wire transfer to the Company of
Federal (same day) funds, by causing DTC to credit the Securities to the account
of the Purchasers at DTC.  The Company will cause the certificates representing
the Securities to be made available to the Purchasers for checking at least
twenty-four hours prior to the Time of Delivery (as defined below) at the office
of DTC or its designated custodian (the "Designated Office").  The time and date
of such delivery and payment shall be, with respect to Firm Securities, 7:00
a.m., San Francisco time, on June 11, 2001 or such other time and date as the
Purchasers and the Company may agree upon in writing and, with respect to the
Optional Securities, 7:00 a.m. San Francisco time, on the date specified by the
Purchasers in the written notice given by the Purchasers of the Purchasers'
election to purchase such Optional Securities, or such other time and date as
the Purchasers and the Company may agree upon in writing.  Such time and date
for delivery of the Firm Securities is herein called the "First Time of
Delivery", such time and date for delivery of the Optional Securities, if not
the First Time of Delivery, is herein called the "Second Time of Delivery", and
each such time and date for delivery is herein called a "Time of Delivery".

     (b) The documents to be delivered at each Time of Delivery by or on behalf
of the parties hereto pursuant to Section 7 hereof, including the cross-receipt
for the Securities and any additional documents requested by the Purchasers
pursuant to Section 7(j) hereof, will be delivered at such time and date at the
offices of Cooley Godward LLP, 3000 El Camino Real, Palo Alto, California

                                       8
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94306 (the "Closing Location"), and the Securities will be delivered at the
Designated Office, all at the Time of Delivery. A meeting will be held at the
Closing Location at 2:00 p.m., San Francisco time, on the New York Business Day
next preceding the Time of Delivery, at which meeting the final drafts of the
documents to be delivered pursuant to the preceding sentence will be available
for review by the parties hereto. For the purposes of this Section 4, "New York
Business Day" shall mean each Monday, Tuesday, Wednesday, Thursday and Friday
which is not a day on which banking institutions in New York are generally
authorized or obligated by law or executive order to close.

     5.  The Company agrees with each of the Purchasers:

     (a) To prepare the Offering Circular in a form approved by you; to make no
amendment or any supplement to the Offering Circular which shall be reasonably
disapproved by you promptly after reasonable notice thereof; and to furnish you
with copies thereof;

     (b) Promptly from time to time to take such action as you may reasonably
request to qualify the Securities and the shares of Stock issuable upon
conversion of the Securities for offering and sale under the securities laws of
such U.S. jurisdictions as you may request and to comply with such laws so as to
permit the continuance of sales and dealings therein in such U.S. jurisdictions
for as long as may be necessary to complete the distribution of the Securities,
provided that in connection therewith the Company shall not be required to
qualify as a foreign corporation or to file a general consent to service of
process or taxation in any jurisdiction;

     (c) To furnish the Purchasers with four copies of the Offering Circular and
each amendment or supplement thereto signed by an authorized officer of the
Company with the independent accountants' report in the Offering Circular, and
any amendment or supplement containing amendments to the financial statements
covered by such report, signed by the accountants, and additional copies thereof
in such quantities as you may from time to time reasonably request, and if, at
any time prior to the expiration of nine months after the date of the Offering
Circular, any event shall have occurred as a result of which the Offering
Circular as then amended or supplemented would include an untrue statement of a
material fact or omit to state any material fact necessary in order to make the
statements therein, in the light of the circumstances under which they were made
when such Offering Circular is delivered, not misleading, or, if for any other
reason it shall be necessary or desirable during such same period to amend or
supplement the Offering Circular, to notify you and upon your request to prepare
and furnish without charge to each Purchaser and to any dealer in securities as
many copies as you may from time to time reasonably request of an amended
Offering Circular or a supplement to the Offering Circular which will correct
such statement or omission or effect such compliance;

     (d) During the period beginning from the date of the Offering Circular and
continuing until the date 90 days after the date of the Offering Circular, not
to offer, sell contract to sell or otherwise dispose of, except as provided
hereunder any securities of the Company that are substantially similar to the
Securities or the Stock, including but not limited to any securities that are
convertible into or exchangeable for, or that represent the right to receive,
Stock or any such substantially similar securities other than (i) pursuant to
employee stock option plans and employee stock purchase plans existing on, or
upon the conversion or exchange of convertible or exchangeable securities
outstanding as of, the date of this Agreement, or upon conversion of the
Securities, (ii) as consideration for acquisitions of businesses, (iii) pursuant
to equipment or lease or facilities financing activities entered into in the
ordinary course of business, or (iv) to a strategic partner of the Company

                                       9
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in conjunction with an agreement involving a technical, manufacturing and/or
marketing collaboration occurring after the date of the Offering Circular,
provided that each recipient of shares pursuant to these clauses (ii) through
(iv) agrees that all such shares remain subject to restrictions substantially
similar to those contained in this subsection; and that the Company will use
reasonable efforts to cause each person who has entered into a Lock-up Agreement
to comply therewith, will not grant any waivers or consents to non-compliance
therewith and will enforce its rights under each such agreement, in each case
unless and to the extent that it shall have obtained your prior consent;

     (e) Not to be or become, at any time prior to the expiration of three years
after the Time of Delivery, an open-end investment company, unit investment
trust, closed-end investment company or face-amount certificate company that is
or is required to be registered under Section 8 of the Investment Company Act;

     (f) At any time when the Company is not subject to Section 13 or 15(d) of
the Exchange Act, for the benefit of holders from time to time of Securities, to
furnish at its expense, upon request, to holders of Securities and prospective
purchasers of securities information (the "Additional Issuer Information")
satisfying the requirements of subsection (d)(4)(i) of Rule 144A under the
Securities Act;

     (g) To use its reasonable efforts to cause the Securities to be eligible
for the PORTAL trading system of the National Association of Securities Dealers,
Inc.;

     (h) To furnish to the holders of the Securities as soon as practicable
after the end of each fiscal year an annual report (including a balance sheet
and statements of income, stockholders' equity and cash flows of the Company and
its consolidated subsidiaries certified by independent public accountants) and,
as soon as practicable after the end of each of the first three quarters of each
fiscal year (beginning with the fiscal quarter ending after the date of the
Offering Circular), consolidated summary financial information of the Company
and its subsidiaries for such quarter in reasonable detail;

     (i) During a period of five years from the date of the Offering Circular,
provided any of the Securities are then outstanding, to furnish to you copies of
all reports or other communications (financial or other) furnished to
stockholders of the Company, and to deliver to you (i) as soon as they are
available, copies of any reports and financial statements furnished to or filed
with the Commission or any securities exchange on which the Securities or any
class of securities of the Company is listed, provided that any reports,
financial statements or other communications that are available by EDGAR need
not be furnished; and (ii) such additional information concerning the business
and financial condition of the Company as you may from time to time reasonably
request (such financial statements to be on a consolidated basis to the extent
the accounts of the Company and its subsidiaries are consolidated in reports
furnished to its stockholders generally or to the Commission);

     (j) During the period of two years after the Time of Delivery, the Company
will not, and will not permit any of its "affiliates" (as defined in Rule 144
under the Securities Act) to, resell any of the Securities which constitute
"restricted securities" under Rule 144 that have been reacquired by any of them;

     (k) To use the net proceeds received by it from the sale of the Securities
pursuant to this Agreement in the manner specified in the Offering Circular
under the caption "Use of Proceeds";

                                       10
<PAGE>

     (l) To reserve and keep available at all times, free of preemptive rights,
shares of Stock for the purpose of enabling the Company to satisfy any
obligations to issue shares of its Stock upon conversion of the Securities; and

     (m) To use its reasonable efforts to list, subject to notice of issuance,
the shares of Stock issuable upon conversion of the Securities on the Nasdaq
National Market.

     6.  The Company covenants and agrees with the several Purchasers that the
Company will pay or cause to be paid the following: (i) the fees, disbursements
and expenses of the Company's counsel and accountants in connection with the
issue of the Securities and the shares of Stock issuable upon conversion of the
Securities and all other expenses in connection with the preparation, printing
and filing of the Preliminary Offering Circular and the Offering Circular and
any amendments and supplements thereto and the mailing and delivering of copies
thereof to the Purchasers and dealers; (ii) the cost of printing or producing
the Blue Sky and Legal Investment Memoranda, if any, in connection with the
offering, purchase, sale and delivery of the Securities; (iii) all expenses in
connection with the qualification of the Securities and the shares of Stock
issuable upon conversion of the Securities for offering and sale under state
securities laws as provided in Section 5(b) hereof, including the fees and
disbursements of counsel for the Purchasers in connection with such
qualification and in connection with the Blue Sky and legal investment surveys;
(iv) any fees charged by securities rating services for rating the Securities;
(v) the cost of preparing the Securities; (vi) the fees and expenses of the
Trustee and any agent of the Trustee and the fees and disbursements of counsel
for the Trustee in connection with the Indenture and the Securities; (vii) any
cost incurred in connection with the designation of the Securities for trading
in PORTAL and the listing of the shares of Stock issuable upon conversion of the
Securities on the Nasdaq National Market; and (viii) all other costs and
expenses incident to the performance of its obligations hereunder which are not
otherwise specifically provided for in this Section.  It is understood, however,
that, except as provided in this Section, and Sections 8 and 11 hereof, the
Purchasers will pay all of their own costs and expenses, including the fees of
their counsel, transfer taxes on resale of any of the Securities by them, and
any advertising expenses connected with any offers they may make.

     7.  The obligations of the Purchasers hereunder, as to the Securities to be
delivered at each Time of Delivery, shall be subject, in their discretion, to
the condition that all representations and warranties and other statements of
the Company herein are, at and as of such Time of Delivery, true and correct,
the condition that the Company shall have performed all of its obligations
hereunder theretofore to be performed, and the following additional conditions:

     (a) Sullivan & Cromwell, counsel for the Purchasers, shall have furnished
to you such opinion or opinions, dated such Time of Delivery, with respect to
such matters as you may reasonably request, and such counsel shall have received
such papers and information as they may reasonably request to enable them to
pass upon such matters;

     (b) Cooley Godward LLP, counsel for the Company, and Patrick Broderick,
Senior Vice President and General Counsel of the Company, shall have furnished
to you their written opinion, dated such Time of Delivery, in form and substance
satisfactory to you, to the effect that:

     In the case of the opinion of Cooley Godward LLP:

                                       11
<PAGE>

     (i)    The Company has been duly incorporated and is validly existing as a
corporation in good standing under the laws of Delaware, with full corporate
power and authority to own or lease its properties and to conduct its business
as described in the Offering Circular;

     (ii)   The Company has an authorized capitalization as set forth in the
Offering Circular, and all of the issued shares of capital stock of the Company
have been duly and validly authorized and issued and are fully paid and
nonassessable; and the shares of Stock initially issuable upon conversion of the
Securities have been duly and validly authorized and reserved for issuance and,
when issued and delivered in accordance with the provisions of the Securities
and the Indenture, will be duly and validly issued and fully paid and non-
assessable, and will conform to the description of the Stock contained in the
Offering Circular under the caption "Description of Capital Stock";

     (iii)  To such counsel's knowledge, the Company is duly qualified to do
business as a foreign corporation and is in good standing as a foreign
corporation authorized to do business in the State of California;

     (iv)   To such counsel's knowledge and other than as set forth in the
Offering Circular, there are no legal or governmental proceedings pending to
which the Company is a party or of which any property of the Company is subject
that would be required to be described in the Offering Circular, to the same
extent as would be required if the Offering Circular were a prospectus included
in a Registration Statement of the Company on Form S-1 under the Securities Act;

     (v)    This Agreement and the Registration Rights Agreement have been duly
authorized, executed and delivered by the Company;

     (vi)   The Securities have been duly authorized, executed, authenticated,
issued and delivered and constitute valid and legally binding obligations of the
Company enforceable in accordance with their terms and entitled to the benefits
provided by the Indenture, subject, as to enforcement, to bankruptcy,
insolvency, reorganization and other laws of general applicability relating to
or affecting creditors' rights and to general equity principles; and the
Securities and the Indenture conform to the descriptions thereof contained in
the Offering Circular under the caption "Description of the Notes" (such counsel
being entitled to rely on the opinion of Sullivan & Cromwell as to matters of
New York law);

     (vii)  The Indenture has been duly authorized, executed and delivered by
the Company and, assuming due authorization, execution and delivery by the
Trustee, constitutes a valid and legally binding instrument, enforceable in
accordance with its terms, subject, as to enforcement, to bankruptcy,
insolvency, reorganization and other laws of general applicability relating to
or affecting creditors' rights and to general equity principles (such counsel
being entitled to rely on the opinion of Sullivan & Cromwell as to matters of
New York law);

     (viii) The issue and sale of the Securities and the compliance by the
Company with all of the provisions of the Securities, the Indenture, the
Registration Rights Agreement and this Agreement and the consummation of the
transactions herein and therein contemplated will not conflict with or result in
a breach or violation of any of the terms or provisions of, or constitute a
default under, any indenture, mortgage, deed of trust, loan agreement or other
agreement

                                       12
<PAGE>

or instrument listed by the Company as an exhibit to the Company's Annual Report
on Form 10-K for the year ended December 31, 2000, nor will such actions result
in any violation of the provisions of the Certificate of Incorporation or By-
laws of the Company or any statute or, to such counsel's knowledge, any rule or
regulation of any governmental agency or body having jurisdiction over the
Company or any of its properties (except for the securities or Blue Sky laws of
the various states as to which such counsel need not express any opinion) or, to
such counsel's knowledge, any order of any court entered against the Company;

     (ix)   No consent, approval, authorization, order, registration or
qualification of or with any governmental agency or body is required for the
offer and sale of the Securities or the consummation by the Company of the
transactions contemplated by this Agreement, the Registration Rights Agreement
or the Indenture, except such as may be required under the Securities Act and
blue sky laws of the various states in connection with registration, pursuant to
the Registration Rights Agreement, of the Securities and the shares of Stock
issuable upon conversion of the Securities and such consents, approvals,
authorizations, registrations or qualifications as may be required under state
securities or Blue Sky laws in connection with the purchase and distribution of
the Securities by the Purchasers;

     (x)    The statements set forth in the Offering Circular under the captions
"Description of the Notes" and "Description of Capital Stock", insofar as they
purport to constitute a summary of the terms of the Securities and the Stock and
under the captions "Certain United States Federal Income Tax Consequences",
insofar as they purport to describe the provisions of the laws and documents
referred to therein, fairly present in all material respects such legal matters
and documents (to the same extent as would be required if the Offering Circular
were a prospectus included in a Registration Statement of the Company on Form S-
1 under the Securities Act);

     (xi)   No registration of the Securities or the shares of Stock issued upon
conversion of the Securities under the Securities Act, and no qualification of
an indenture under the Trust Indenture Act with respect to the Securities, is
required for the offer and sale by the Company and the offer and initial resale
of the Securities by the Purchasers in the manner contemplated by this Agreement
assuming (i) the accuracy of, and compliance with, the Purchasers'
representations and agreements contained in Section 3 of the Purchase Agreement,
(ii) the accuracy of the representations of the Company set forth in Sections
1(m), 1(n), 1(p) and 1(q) of the Purchase Agreement and (iii) the Securities are
sold pursuant to the Offering Circular;

     (xii)  The Company is not an "investment company", as such term is defined
in the Investment Company Act;

     (xiii) To such counsel's knowledge, the Company is licensed to use, or
owns, each patent application and patent listed on Exhibit 2 to its opinion
(such exhibit to be consistent with the draft exhibit previously furnished to
Sullivan & Cromwell) (the "Patent Portfolio");

     (xiv)  To such counsel's knowledge, except as otherwise described in
Exhibit 2, no third party has any rights to the patent applications and patents
listed in the Patent Portfolio for the manufacture, use or sale of Integrilin;

                                       13
<PAGE>

         (xv)     The Company's United States patent applications listed in the
     Patent Portfolio have been prepared and filed in the United States Patent
     and Trademark Office (the "USPTO") in a form and with accompanying papers
     that are acceptable to the USPTO for the purposes of according each such
     application a filing date and serial number, and of placing each such
     application in condition for eventual examination on the merits as to
     patentability.  For each such United States application, an Official Filing
     Receipt has been received from the USPTO.  As to each of such applications,
     such counsel is not aware of any material defect of form in preparation or
     filing; and all United States patent applications in the Patent Portfolio
     have been issued as United States patents;

         (xvi)    The statements contained in the Offering Circular under the
     caption "Risk Factors--If we are unable to protect our patents and
     proprietary rights we may not be able to compete successfully" and in the
     Form 10-K attached to the Offering Circular under the caption "Patents,
     Proprietary Rights and Licenses" as they pertain to the Patent Portfolio,
     insofar as such statements constitute matters of law, are a fair and
     accurate summary of the matters set forth therein, to the extent required
     under the Act and the applicable Rules and Regulations;

         (xvii)   To such counsel's knowledge, other than as set forth in the
     Offering Circular, the Company has received no notice of any infringement
     of, conflict with or misappropriation by a third party of any claim for
     which patent applications have been filed with respect to the Patent
     Portfolio or notice of any unresolved infringement of, or conflict with or
     proceedings against or misappropriation by the Company of any patents,
     trade secrets, trademarks, trade names, copyrights or other proprietary
     rights of a third party, which, either individually or in the aggregate, is
     material to the Company;

         (xviii)  To such counsel's knowledge, the Company or its licensor is
     the sole assignee of record for each patent application and patent listed
     in the Patent Portfolio.  Except as otherwise noted in the Patent
     Portfolio, for each of the United States patent applications and patents
     listed in the Patent Portfolio, the assignments by the named inventors have
     been submitted to the USPTO and those assignments have been recorded in the
     Patent Office title records; and

         (xix)    To such counsel's knowledge, as to each of the Company's
     foreign patent applications listed in the Patent Portfolio, the
     applications have either (a) except as noted in the Patent Portfolio, been
     submitted to patent firms in the respective foreign countries with
     instructions to file the applications in the patent offices of those
     countries naming the Company as the applicant of record, or (b) as to
     certain Patent Cooperation Treaty applications, been submitted directly to
     the relevant receiving office naming the Company as the applicant of
     record. To such counsel's knowledge and except as noted in the Patent
     Portfolio, as to each of such applications, the Company has not received
     notice from any foreign filing authority of any material defect of form in
     preparation or filing that the Company has not cured within the relevant
     cure period.

         Subject to the final sentence of this paragraph, such counsel shall
     also state that they have no reason to believe that the Offering Circular
     and any further amendments or

                                       14
<PAGE>

     supplements thereto made by the Company prior to such Time of Delivery
     (other than the financial statements, including supporting schedules and
     other financial data derived from accounting records and included therein,
     as to which such counsel need express no opinion) contained as of its date
     or contains as of such Time of Delivery an untrue statement of a material
     fact or omitted or omits, as the case may be, to state a material fact
     necessary to make the statements therein, in the light of the circumstances
     under which they were made, not misleading. Such counsel will be required
     to provide the statement described in this paragraph only if counsel for
     the Purchasers is concurrently providing a similar statement to the
     Purchasers pursuant to Section 7(a).

         The opinion of Cooley Godward LLP described in this Section 7(b) shall
     be rendered to you at the request of the Company and shall so state
     therein.  In providing the statement with respect to the matters covered in
     the last paragraph of Section 7(b), Cooley Godward LLP may state that its
     statement and belief are based upon its participation in the preparation,
     together with the Purchasers, Purchaser's counsel and the Company's
     independent accountants, of the Offering Circular and any amendments and
     supplements thereto and review and discussion of the contents thereof, but
     are without independent check or verification except as specified;

         In the case of the opinion of Patrick Broderick:

         (i)   The Exchange Reports (other than the financial statements and
     related schedules therein, as to which such counsel need express no
     opinion), when they were filed with the Commission, complied as to form in
     all material respects with the requirements of the Exchange Act, and the
     rules and regulations of the Commission thereunder; and such counsel has no
     reason to believe that any of such documents, when they were so filed,
     contained an untrue statement of a material fact or omitted to state a
     material fact necessary in order to make the statements therein, in the
     light of the circumstances under which they were made when such documents
     were so filed, not misleading;

     (c) On the date of the Offering Circular prior to the execution of this
Agreement and also at such Time of Delivery, Ernst & Young LLP shall have
furnished to you a letter or letters, dated the respective dates of delivery
thereof, in form and substance satisfactory to you, to the effect set forth in
Annex I hereto;

     (d) (i) The Company shall not have sustained since the date of the latest
audited financial statements included in the Offering Circular any loss or
interference with its business from fire, explosion, flood or other calamity,
whether or not covered by insurance, or from any labor dispute or court or
governmental action, order or decree, otherwise than as set forth or
contemplated in the Offering Circular, and (ii) since the respective dates as of
which information is given in the Offering Circular there shall not have been
any change in the capital stock or long-term debt of the Company or any change,
or any development involving a prospective change, in or affecting the general
affairs, management, financial position, stockholders' equity or results of
operations of the Company, otherwise than as set forth or contemplated in the
Offering Circular, the effect of which, in any such case described in clause (i)
or (ii), is in your judgment so material and adverse as to make it impracticable
or inadvisable to proceed with the offering or the delivery of the Securities on
the terms and in the manner contemplated in this Agreement and  in the Offering
Circular;

                                       15
<PAGE>

     (e) On or after the date hereof (i) no downgrading shall have occurred in
the rating accorded the Company's debt securities by any "nationally recognized
statistical rating organization", as that term is defined by the Commission for
purposes of Rule 436(g)(2) under the Securities Act, and (ii) no such
organization shall have publicly announced that it has under surveillance or
review, with possible negative implications, its rating of any of the Company's
debt securities;

     (f) On or after the date hereof there shall not have occurred any of the
following: (i) a suspension or material limitation in trading in securities
generally on the New York Stock Exchange or on the Nasdaq National Market; (ii)
a suspension or material limitation in trading in the Company's securities on
the Nasdaq National Market; (iii) a general moratorium on commercial banking
activities declared by either Federal or New York State authorities; or (iv) the
outbreak or escalation of hostilities involving the United States or the
declaration by the United States of a national emergency or war, if the effect
of any such event specified in this clause (iv) in the judgment of the
Representatives makes it impracticable or inadvisable to proceed with the
offering or the delivery of the Securities on the terms and in the manner
contemplated in the Offering Circular;

     (g) The Securities shall have been designated for trading on PORTAL;

     (h) Each Lock-up Agreement shall have been duly executed and delivered to
the Company and you, and there shall have occurred no breach of any Lock-up
Agreement;

     (i) The shares of Stock issuable upon conversion of the Securities shall
have been duly listed, subject to notice of issuance, on the Nasdaq National
Market; and

     (j) The Company shall have furnished or caused to be furnished to you at
such Time of Delivery certificates of officers of the Company satisfactory to
you as to the accuracy of the representations and warranties of the Company
herein at and as of such Time of Delivery, as to the performance by the Company
of all of its obligations hereunder to be performed at or prior to such Time of
Delivery, as to the matters set forth in subsection (d) of this Section and as
to such other matters as you may reasonably request.

     8.  (a)  The Company will indemnify and hold harmless each Purchaser
against any losses, claims, damages or liabilities, joint or several, to which
such Purchaser may become subject, under the Securities Act or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon an untrue statement or alleged untrue
statement of a material fact contained in any preliminary offering circular or
the Offering Circular, or any amendment or supplement thereto, or arise out of
or are based upon the omission or alleged omission to state therein a material
fact necessary to make the statements therein not misleading, and will reimburse
each Purchaser for any legal or other expenses reasonably incurred by such
Purchaser in connection with investigating or defending any such action or claim
as such expenses are incurred; provided, however, that the Company shall not be
liable in any such case to the extent that any such loss, claim, damage or
liability arises out of or is based upon an untrue statement or alleged untrue
statement or omission or alleged omission made in any preliminary offering
circular or the Offering Circular or any such amendment or supplement in
reliance upon and in conformity with written information furnished to the
Company by any Purchaser through Goldman, Sachs & Co. expressly for use therein.

                                       16
<PAGE>

     (b) Each Purchaser will indemnify and hold harmless the Company against any
losses, claims, damages or liabilities to which the Company may become subject,
under the Securities Act or otherwise, insofar as such losses, claims, damages
or liabilities (or actions in respect thereof) arise out of or are based upon an
untrue statement or alleged untrue statement of a material fact contained in any
preliminary offering circular or the Offering Circular, or any amendment or
supplement thereto, or arise out of or are based upon the omission or alleged
omission to state therein a material fact or necessary to make the statements
therein not misleading, in each case to the extent, but only to the extent, that
such untrue statement or alleged untrue statement or omission or alleged
omission was made in any preliminary offering circular or the Offering Circular
or any such amendment or supplement in reliance upon and in conformity with
written information furnished to the Company by such Purchaser through Goldman,
Sachs & Co. expressly for use therein; and will reimburse the Company for any
legal or other expenses reasonably incurred by the Company in connection with
investigating or defending any such action or claim as such expenses are
incurred.

     (c) Promptly after receipt by an indemnified party under subsection (a) or
(b) above of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party under such subsection, notify the indemnifying party in writing of the
commencement thereof; but the omission so to notify the indemnifying party shall
not relieve it from any liability which it may have to any indemnified party
otherwise than under such subsection.  In case any such action shall be brought
against any indemnified party and it shall notify the indemnifying party of the
commencement thereof, the indemnifying party shall be entitled to participate
therein and, to the extent that it shall wish, jointly with any other
indemnifying party similarly notified, to assume the defense thereof, with
counsel reasonably satisfactory to such indemnified party (who shall not, except
with the consent of the indemnified party, be counsel to the indemnifying
party), and, after notice from the indemnifying party to such indemnified party
of its election so to assume the defense thereof, the indemnifying party shall
not be liable to such indemnified party under such subsection for any legal
expenses of other counsel or any other expenses, in each case subsequently
incurred by such indemnified party, in connection with the defense thereof other
than reasonable costs of investigation.  No indemnifying party shall, without
the written consent of the indemnified party, effect the settlement or
compromise of, or consent to the entry of any judgment with respect to, any
pending or threatened action or claim in respect of which indemnification or
contribution may be sought hereunder (whether or not the indemnified party is an
actual or potential party to such action or claim) unless such settlement,
compromise or judgment (i) includes an unconditional release of the indemnified
party from all liability arising out of such action or claim and (ii) does not
include a statement as to, or an admission of, fault, culpability or a failure
to act, by or on behalf of any indemnified party.

     (d) If the indemnification provided for in this Section 8 is unavailable to
or insufficient to hold harmless an indemnified party under subsection (a) or
(b) above in respect of any losses, claims, damages or liabilities (or actions
in respect thereof) referred to therein, then each indemnifying party shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages or liabilities (or actions in respect thereof)
in such proportion as is appropriate to reflect the relative benefits received
by the Company on the one hand and the Purchasers on the other from the offering
of the Securities.  If, however, the allocation provided by the immediately
preceding sentence is not permitted by applicable law or if the indemnified
party failed to give the notice required under subsection (c) above, then each
indemnifying party shall contribute to such amount paid or payable by such
indemnified party in such proportion as is appropriate to reflect not only such
relative benefits but also the relative fault of the Company on the one hand and
the

                                       17
<PAGE>

Purchasers on the other in connection with the statements or omissions which
resulted in such losses, claims, damages or liabilities (or actions in respect
thereof), as well as any other relevant equitable considerations.  The relative
benefits received by the Company on the one hand and the Purchasers on the other
shall be deemed to be in the same proportion as the total net proceeds from the
offering (before deducting expenses) received by the Company bear to the total
underwriting discounts and commissions received by the Purchasers, in each case
as set forth in the Offering Circular.  The relative fault 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 on the one hand or
the Purchasers on the other and the parties' relative intent, knowledge, access
to information and opportunity to correct or prevent such statement or omission.
The Company and the Purchasers agree that it would not be just and equitable if
contribution pursuant to this subsection (d) were determined by pro rata
allocation (even if the Purchasers were treated as one entity for such purpose)
or by any other method of allocation which does not take account of the
equitable considerations referred to above in this subsection (d).  The amount
paid or payable by an indemnified party as a result of the losses, claims,
damages or liabilities (or actions in respect thereof) referred to above in this
subsection (d) shall be deemed to include any legal or other expenses reasonably
incurred by such indemnified party in connection with investigating or defending
any such action or claim.  Notwithstanding the provisions of this subsection
(d), no Purchaser shall be required to contribute any amount in excess of the
amount by which the total price at which the Securities underwritten by it and
distributed to investors were offered to investors exceeds the amount of any
damages which such Purchaser has otherwise been required to pay by reason of
such untrue or alleged untrue statement or omission or alleged omission. The
Purchasers' obligations in this subsection (d) to contribute are several in
proportion to their respective underwriting obligations and not joint.

     (e) The obligations of the Company under this Section 8 shall be in
addition to any liability which the Company may otherwise have and shall extend,
upon the same terms and conditions, to each person, if any, who controls any
Purchaser within the meaning of the Securities Act; and the obligations of the
Purchasers under this Section 8 shall be in addition to any liability which the
respective Purchasers may otherwise have and shall extend, upon the same terms
and conditions, to each officer and director of the Company and to each person,
if any, who controls the Company within the meaning of the Securities Act.

     9.  (a)  If any Purchaser shall default in its obligation to purchase the
Securities which it has agreed to purchase hereunder, you may in your discretion
arrange for you or another party or other parties to purchase such Securities on
the terms contained herein.  If within thirty-six hours after such default by
any Purchaser you do not arrange for the purchase of such Securities, then the
Company shall be entitled to a further period of thirty-six hours within which
to procure another party or other parties satisfactory to you to purchase such
Securities on such terms.  In the event that, within the respective prescribed
periods, you notify the Company that you have so arranged for the purchase of
such Securities, or the Company notifies you that it has so arranged for the
purchase of such Securities, you or the Company shall have the right to postpone
the Time of Delivery for a period of not more than  seven days, in order to
effect whatever changes may thereby be made necessary in the Offering Circular,
or in any other documents or arrangements, and the Company agrees to prepare
promptly any amendments to the Offering Circular which in your opinion may
thereby be made necessary.  The term "Purchaser" as used in this Agreement shall
include any person substituted under this Section with like effect as if such
person had originally been a party to this Agreement with respect to such
Securities.

                                       18
<PAGE>

     (b)  If, after giving effect to any arrangements for the purchase of the
Securities of a defaulting Purchaser or Purchasers by you and the Company as
provided in subsection (a) above, the aggregate principal amount of such
Securities which remains unpurchased does not exceed one-eleventh of the
aggregate principal amount of all the Securities, then the Company shall have
the right to require each non-defaulting Purchaser to purchase the principal
amount of Securities which such Purchaser agreed to purchase hereunder and, in
addition, to require each non-defaulting Purchaser to purchase its pro rata
share (based on the principal amount of Securities which such Purchaser agreed
to purchase hereunder) of the Securities of such defaulting Purchaser or
Purchasers for which such arrangements have not been made; but nothing herein
shall relieve a defaulting Purchaser from liability for its default.

     (c)  If, after giving effect to any arrangements for the purchase of the
Securities of a defaulting Purchaser or Purchasers by you and the Company as
provided in subsection (a) above, the aggregate principal amount of Securities
which remains unpurchased exceeds one-eleventh of the aggregate principal amount
of all the Securities, or if the Company shall not exercise the right described
in subsection (b) above to require non-defaulting Purchasers to purchase
Securities of a defaulting Purchaser or Purchasers, then this Agreement shall
thereupon terminate, without liability on the part of any non-defaulting
Purchaser or the Company, except for the expenses to be borne by the Company and
the Purchasers as provided in Section 6 hereof and the indemnity and
contribution agreements in Section 8 hereof; but nothing herein shall relieve a
defaulting Purchaser from liability for its default.

     10.  The respective indemnities, agreements, representations, warranties
and other statements of the Company and the several Purchasers, as set forth in
this Agreement or made by or on behalf of them, respectively, pursuant to this
Agreement, shall remain in full force and effect, regardless of any
investigation (or any statement as to the results thereof) made by or on behalf
of any Purchaser or any controlling person of any Purchaser, or the Company, or
any officer or director or controlling person of the Company, and shall survive
delivery of and payment for the Securities.

     11.  If this Agreement shall be terminated pursuant to Section 9 hereof,
the Company shall not then be under any liability to any Purchaser except as
provided in Sections 6 and 8 hereof; but, if for any other reason, the
Securities are not delivered by or on behalf of the Company as provided herein,
the Company will reimburse the Purchasers through you for all out-of-pocket
expenses approved in writing by you, including fees and disbursements of
counsel, reasonably incurred by the Purchasers in making preparations for the
purchase, sale and delivery of the Securities, but the Company shall then be
under no further liability to any Purchaser except as provided in Sections 6 and
8 hereof.

     12.  In all dealings hereunder, you shall act on behalf of each of the
Purchasers, and the parties hereto shall be entitled to act and rely upon any
statement, request, notice or agreement on behalf of any Purchaser made or given
by you jointly or by Goldman, Sachs & Co. on behalf of you as the
Representatives.

     All statements, requests, notices and agreements hereunder shall be in
writing, and if to the Purchasers shall be delivered or sent by mail, telex or
facsimile transmission to you as the Representatives in care of Goldman, Sachs &
Co., 32 Old Slip, 21st Floor, New York, New York 10005, Attention: Registration
Department; and if to the Company shall be delivered or sent by mail, telex or
facsimile transmission to the address of the Company set forth in the Offering
Circular,

                                      19
<PAGE>

Attention: General Counsel; provided, however, that any notice to a Purchaser
pursuant to Section 8(c) hereof shall be delivered or sent by mail, telex or
facsimile transmission to such Purchaser at its address set forth in its
Purchasers' Questionnaire, or telex constituting such Questionnaire, which
address will be supplied to the Company by you upon request. Any such
statements, requests, notices or agreements shall take effect upon receipt
thereof.

     13.  This Agreement shall be binding upon, and inure solely to the benefit
of, the Purchasers, the Company and, to the extent provided in Sections 8 and 10
hereof, the officers and directors of the Company and each person who controls
the Company or any Purchaser, and their respective heirs, executors,
administrators, successors and assigns, and no other person shall acquire or
have any right under or by virtue of this Agreement. No purchaser of any of the
Securities from any Purchaser shall be deemed a successor or assign by reason
merely of such purchase.

     14.  Time shall be of the essence of this Agreement.

     15.  This Agreement shall be governed by and construed in accordance with
the laws of the State of New York.

     16.  This Agreement may be executed by any one or more of the parties
hereto in any number of counterparts, each of which shall be deemed to be an
original, but all such respective counterparts shall together constitute one and
the same instrument.

     17.  The Company is authorized, subject to applicable law, to disclose any
and all aspects of this potential transaction that are necessary to support any
U.S. federal income tax benefits expected to be claimed with respect to such
transaction, without the Purchasers imposing any limitation of any kind.

                                      20
<PAGE>

     If the foregoing is in accordance with your understanding, please sign and
return to us six counterparts hereof, and upon the acceptance hereof by you, on
behalf of each of the Purchasers, this letter and such acceptance hereof shall
constitute a binding agreement between each of the Purchasers and the Company.
It is understood that your acceptance of this letter on behalf of each of the
Purchasers is pursuant to the authority set forth in a form of Agreement among
Purchasers, the form of which shall be submitted to the Company for examination
upon request, but without warranty on your part as to the authority of the
signers thereof.

                                        Very truly yours,

                                        COR THERAPEUTICS, INC.

                                        By: /s/ Patrick A. Broderick
                                            -------------------------------
                                            Name: Patrick A. Broderick
                                            Title: Senior Vice President,
                                                     General Counsel

Accepted as of the date hereof:

Goldman, Sachs & Co.
Robertson Stephens, Inc.
Credit Suisse First Boston Corporation
CIBC World Markets Corp.
Needham & Company, Inc.


By:  /s/ Goldman, Sachs & Co.
    ----------------------------------
          (Goldman, Sachs & Co.)

        On behalf of each of the Purchasers

                                      21
<PAGE>

                            SCHEDULE I

<TABLE>
<CAPTION>
                                                                                                  Principal Amount of
                                                                                                  Optional Securities
                                                                          Principal Amount of      to be Purchased if
                                                                           Firm Securities to        Maximum Option
                                                                              be Purchased              Exercised
                                                                          -------------------     -------------------
<S>                                                                       <C>                     <C>
Goldman, Sachs & Co................................................          $162,500,000              $32,500,000
Robertson Stephens, Inc............................................            27,500,000                5,500,000
Credit Suisse First Boston Corporation.............................            25,000,000                5,000,000
CIBC World Markets Corp............................................            25,000,000                5,000,000
Needham & Company, Inc.............................................            10,000,000                2,000,000



                                                                          -------------------     -------------------
       Total.......................................................          $250,000,000              $50,000,000
                                                                          ===================     ===================
</TABLE>

                                      22
<PAGE>

                                                                         ANNEX I

     Pursuant to Section 7(c) of the Purchase Agreement, the accountants shall
furnish letters to the Purchasers to the effect that:

         (i)   They are independent certified public accountants with respect to
     the Company and its subsidiaries within the meaning of the Securities
     Exchange Act of 1934 (the "Exchange Act") and the applicable published
     rules and regulations thereunder;

         (ii)  In their opinion, the consolidated financial statements and
     financial statement schedules audited by them and included in the Offering
     Circular comply as to form in all material respects with the applicable
     requirements of the Exchange Act and the related published rules and
     regulations;

         (iii) The unaudited selected financial information with respect to the
     consolidated results of operations and financial position of the Company
     for the five most recent fiscal years included in the Offering Circular
     agrees with the corresponding amounts (after restatements where applicable)
     in the audited consolidated financial statements for such five fiscal
     years;

         (iv)  On the basis of limited procedures not constituting an audit in
     accordance with generally accepted auditing standards, consisting of a
     reading of the unaudited financial statements and other information
     referred to below, a reading of the latest available interim financial
     statements of the Company and its subsidiaries, inspection of the minute
     books of the Company and its subsidiaries since the date of the latest
     audited financial statements included in the Offering Circular, inquiries
     of officials of the Company and its subsidiaries responsible for financial
     and accounting matters and such other inquiries and procedures as may be
     specified in such letter, nothing came to their attention that caused them
     to believe that:

               (A)  the unaudited consolidated statements of income,
          consolidated balance sheets and consolidated statements of cash flows
          included in the Offering Circular are not in conformity with generally
          accepted accounting principles applied on the basis substantially
          consistent with the basis for the unaudited condensed consolidated
          statements of income, consolidated balance sheets and consolidated
          statements of cash flows included in the Offering Circular;

               (B)  any other unaudited income statement data and balance sheet
          items included in the Offering Circular do not agree with the
          corresponding items in the unaudited consolidated financial statements
          from which such data and items were derived, and any such unaudited
          data and items were not determined on a basis substantially consistent
          with the basis for the corresponding amounts in the audited
          consolidated financial statements included in the Offering Circular;

               (C)  the unaudited financial statements which were not included
          in the Offering Circular but from which were derived any unaudited
          condensed financial statements referred to in clause (A) and any
          unaudited income statement data and balance sheet items included in
          the Offering Circular and referred to in clause (B) were not
<PAGE>

          determined on a basis substantially consistent with the basis for the
          audited consolidated financial statements included in the Offering
          Circular;

               (D)  any unaudited pro forma consolidated condensed financial
          statements included in the Offering Circular do not comply as to form
          in all material respects with the applicable accounting requirements
          or the pro forma adjustments have not been properly applied to the
          historical amounts in the compilation of those statements;

               (E)  as of a specified date not more than five days prior to the
          date of such letter, there have been any changes in the consolidated
          capital stock (other than issuances of capital stock upon exercise of
          options and stock appreciation rights and pursuant to the Company's
          employee stock purchase plan, upon earn-outs of performance shares and
          upon conversions of convertible securities, in each case which were
          outstanding on the date of the latest financial statements included in
          the Offering Circular or any increase in the consolidated long-term
          debt of the Company and its subsidiaries, or any decreases in
          consolidated net current assets or stockholders' equity or other items
          specified by the Representatives, or any increases in any items
          specified by the Representatives, in each case as compared with
          amounts shown in the latest balance sheet included in the Offering
          Circular except in each case for changes, increases or decreases which
          the Offering Circular discloses have occurred or may occur or which
          are described in such letter; and

               (F)  for the period from the date of the latest financial
          statements included in the Offering Circular to the specified date
          referred to in clause (E) there were any decreases in consolidated net
          revenues or operating profit or the total or per share amounts of
          consolidated net income or other items specified by the
          Representatives, or any increases in any items specified by the
          Representatives, in each case as compared with the comparable period
          of the preceding year and with any other period of corresponding
          length specified by the Representatives, except in each case for
          decreases or increases which the Offering Circular discloses have
          occurred or may occur or which are described in such letter; and

         (v)   In addition to the examination referred to in their report(s)
     included in the Offering Circular and the limited procedures, inspection of
     minute books, inquiries and other procedures referred to in paragraphs
     (iii) and (iv) above, they have carried out certain specified procedures,
     not constituting an audit in accordance with generally accepted auditing
     standards, with respect to certain amounts, percentages and financial
     information specified by the Representatives, which are derived from the
     general accounting records of the Company and its subsidiaries, which
     appear in the Offering Circular, and have compared certain of such amounts,
     percentages and financial information with the accounting records of the
     Company and its subsidiaries and have found them to be in agreement.

                                       2
<PAGE>

                                   EXHIBIT A

                         REGISTRATION RIGHTS AGREEMENT
<PAGE>

                                   EXHIBIT B

                            COR Therapeutics, Inc.

                               Lock-Up Agreement

                           Dated as of June __, 2001

Goldman, Sachs & Co.
Robertson Stephens, Inc.
Credit Suisse First Boston Corporation
CIBC World Markets Corp.
Needham & Company, Inc.
c/o Goldman, Sachs & Co.
85 Broad Street
New York, NY 10004.

     Re:  COR Therapeutics, Inc. - Lock-Up Agreement
          ------------------------------------------

Ladies and Gentlemen:

     The undersigned understands that you, as representatives (the
"Representatives"), propose to enter into a Purchase Agreement on behalf of the
several Purchasers named in Schedule I to such agreement (collectively, the
"Purchasers"), with COR Therapeutic, Inc., a Delaware corporation (the
"Company"), providing for an offering of Convertible Senior Notes (the "Notes")
of the Company that will be convertible into shares of the Common Stock of the
Company (the "Common Stock").

     In consideration of the agreement by the Purchasers to offer and sell the
Notes, and of other good and valuable consideration the receipt and sufficiency
of which are hereby acknowledged, the undersigned agrees that, during the period
beginning from the date of the final Offering Circular covering the offering of
the Notes and continuing to and including the date 90 days after the date of
such final Offering Circular (the "Lock-Up Period"), the undersigned will not
offer, sell, contract to sell, pledge, grant any option to purchase, make any
short sale or otherwise dispose of, or exercise any registration rights with
respect to, any shares of Common Stock of the Company, or any options or
warrants to purchase any shares of Common Stock of the Company, or any
securities convertible into, exchangeable for or that represent the right to
receive shares of Common Stock of the Company, whether now owned or hereinafter
acquired, owned directly by the undersigned (including holding as a custodian)
or with respect to which the undersigned has beneficial ownership within the
rules and regulations of the Securities and Exchange Commission (the "SEC")
(collectively the "Undersigned's Shares").
<PAGE>

     The foregoing restriction is expressly agreed to preclude the undersigned
from engaging in any hedging or other transaction which is designed to or which
reasonably could be expected to lead to or result in a sale or disposition of
the Undersigned's Shares even if such Shares would be disposed of by someone
other than the undersigned. Such prohibited hedging or other transactions would
include without limitation any short sale or any purchase, sale or grant of any
right (including without limitation any put or call option) with respect to any
of the Undersigned's Shares or with respect to any security that includes,
relates to, or derives any significant part of its value from such Shares.

     Notwithstanding the foregoing, the undersigned may transfer the
Undersigned's Shares (i) as a bona fide gift or gifts, provided that the donee
or donees thereof, if not a bona fide charity, agree to be bound in writing by
the restrictions set forth herein, (ii) to any trust for the direct or indirect
benefit of the undersigned or the immediate family of the undersigned, provided
that the trustee of the trust agrees to be bound in writing by the restrictions
set forth herein, and provided further that any such transfer shall not involve
a disposition for value, (iii) with the prior written consent of Goldman, Sachs
& Co. on behalf of the Purchasers, or (iv) after the first 60 days of the Lock-
Up Period, the undersigned may transfer up to ten percent (10%) of the
Undersigned's Shares without any restrictions pursuant to this Lock-Up
Agreement. For purposes of this Lock-Up Agreement, "immediate family" shall mean
any relationship by blood, marriage or adoption, not more remote than first
cousin. The undersigned now has, and, except as contemplated by clause (i),
(ii), (iii) or (iv) above, for the duration of this Lock-Up Agreement will have,
good and marketable title to the Undersigned's Shares, free and clear of all
liens, encumbrances, and claims whatsoever. The undersigned also agrees and
consents to the entry of stop transfer instructions with the Company's transfer
agent and registrar against the transfer of the Undersigned's Shares except in
compliance with the foregoing restrictions.

     The undersigned understands that the Company and the Purchasers are relying
upon this Lock-Up Agreement in proceeding toward consummation of the offering.
The undersigned further understands that this Lock-Up Agreement is irrevocable
and shall be binding upon the undersigned's heirs, legal representatives,
successors, and assigns.

                              Very truly yours,

                              ________________________________________

                              Exact Name of Shareholder

                              ________________________________________

                              Authorized Signature

                              ________________________________________

                              Title
<PAGE>

                                  EXHIBIT B-1


List of persons to sign
Lock-Up Agreements:
-------------------


Vaughn M. Kailian
Charles J. Homcy
Shaun R. Coughlin
James T. Doluisio
Jerry T. Jackson
Ernest Mario
Lee Rauch
Patrick Broderick
Ginger L. Graham
Michael G. McCaffery
Peter S. Roddy