OSI PHARMACEUTICALS INC
S-3, EX-1, 2000-09-29
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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<PAGE>   1
                                                                       EXHIBIT 1


                             UNDERWRITING AGREEMENT



                               [October __, 2000]


Robertson Stephens, Inc.
Lehman Brothers Inc.
Prudential Securities Incorporated
Lazard Freres & Co. LLC
Adams, Harkness & Hill, Inc.
   As Representatives of the several Underwriters
c/o FleetBoston Robertson Stephens Inc.
555 California Street, Suite 2600
San Francisco, CA  94104


Ladies and Gentlemen:

                  INTRODUCTORY. OSI Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), proposes to issue and sell to the several
underwriters named in Schedule A (the "Underwriters") an aggregate of [___]
shares (the "Firm Shares") of its Common Stock, par value $.01 per share (the
"Common Shares"). In addition, the Company has granted to the Underwriters an
option to purchase up to an additional [___] Common Shares (the "Option Shares")
as provided in Section 2. The Firm Shares and, if and to the extent such option
is exercised, the Option Shares are collectively called the "Shares". Robertson
Stephens, Inc. ("Robertson Stephens"), Lehman Brothers Inc., Prudential
Securities Incorporated, Lazard Freres & Co. LLC, and Adams, Harkness & Hill,
Inc. have agreed to act as representatives of the several Underwriters (in such
capacity, the "Representatives") in connection with the offering and sale of the
Shares.

                  The Company has prepared and filed with the Securities and
Exchange Commission (the "Commission") a registration statement on Form S-3
(File No. 333-[___]), which contains a form of prospectus, subject to
completion, to be used in connection with the public offering and sale of the
Shares. Each such prospectus, subject to completion, used in connection with
such public offering is called a "preliminary prospectus". Such registration
statement, as amended, including the financial statements, exhibits and
schedules thereto, in the form in which it was declared effective by the
Commission under the Securities Act of 1933 and the rules and regulations
promulgated thereunder (collectively, the "Securities Act"), including all
documents incorporated or deemed to be incorporated by reference therein and any
information deemed to be a part thereof at the time of effectiveness pursuant to
Rule 430A or 434 under the Securities Act or the Securities Exchange Act of 1934
and the rules and
<PAGE>   2

regulations promulgated thereunder (collectively, the "Exchange Act"), is called
the "Registration Statement". Any registration statement filed by the Company
pursuant to Rule 462(b) under the Securities Act is called the "Rule 462(b)
Registration Statement", and from and after the date and time of filing of the
Rule 462(b) Registration Statement the term "Registration Statement" shall
include the Rule 462(b) Registration Statement. Such prospectus, in the form
first used by the Underwriters to confirm sales of the Shares, is called the
"Prospectus". All references in this Agreement to the Registration Statement,
the Rule 462(b) Registration Statement, a preliminary prospectus, the Prospectus
or any amendments or supplements to any of the foregoing, shall include any copy
thereof filed with the Commission pursuant to its Electronic Data Gathering,
Analysis and Retrieval System ("EDGAR"). All references in this Agreement to
financial statements and schedules and other information which is "contained,"
"included" or "stated" in the Registration Statement or the Prospectus (and all
other references of like import) shall be deemed to mean and include all such
financial statements and schedules and other information which is or is deemed
to be incorporated by reference in the Registration Statement or the Prospectus,
as the case may be; and all references in this Agreement to amendments or
supplements to the Registration Statement or the Prospectus shall be deemed to
mean and include the filing of any document under the Exchange Act which is or
is deemed to be incorporated by reference in the Registration Statement or the
Prospectus, as the case may be.

                  The Company hereby confirms its agreements with the
Underwriters as follows:

         SECTION 1.        REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

                  The Company hereby represents, warrants and covenants to each
Underwriter as follows:

         (a)      Compliance with Registration Requirements. The Registration
Statement and any Rule 462(b) Registration Statement have been declared
effective by the Commission under the Securities Act. The Company has complied
to the Commission's satisfaction with all requests of the Commission for
additional or supplemental information. No stop order suspending the
effectiveness of the Registration Statement or any Rule 462(b) Registration
Statement is in effect and no proceedings for such purpose have been instituted
or are pending or, to the best knowledge of the Company, are contemplated or
threatened by the Commission.

                  Each preliminary prospectus and the Prospectus when filed
complied in all material respects with the Securities Act and, if filed by
electronic transmission pursuant to EDGAR (except as may be permitted by
Regulation S-T under the Securities Act), was identical to the copy thereof
delivered to the Underwriters for use in connection with the offer and sale of
the Shares. Each of the Registration Statement, any Rule 462(b) Registration
Statement and any post-effective amendment thereto, at the time it became
effective and at all subsequent times, complied and will comply in all material
respects with the Securities Act and did not and will not contain any 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 not misleading. Each
preliminary prospectus, as of its date, and the Prospectus, as amended or
supplemented, as of its date and at all subsequent times through the 30th day
after the date hereof, did not and will not contain any 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. The representations and warranties set forth in the two
immediately preceding sentences do not apply to statements in or omissions from
the Registration Statement, any Rule 462(b) Registration Statement, or any
post-effective amendment thereto, or the Prospectus, or any amendments or
supplements thereto, made in reliance upon and in


                                       2.
<PAGE>   3

conformity with information relating to any Underwriter furnished to the Company
in writing by the Representatives expressly for use therein. There are no
contracts or other documents required to be described in the Prospectus or to be
filed as exhibits to the Registration Statement which have not been described or
filed as required.

         (b)      Offering Materials Furnished to Underwriters. The Company has
delivered to each Representative one complete conformed copy of the Registration
Statement and of each consent and certificate of experts filed as a part
thereof, and conformed copies of the Registration Statement (without exhibits)
and preliminary prospectuses and the Prospectus, as amended or supplemented, in
such quantities and at such places as such Representative has reasonably
requested for each of the Underwriters.

         (c)      Distribution of Offering Material By the Company. The Company
has not distributed and will not distribute, prior to the later of the Second
Closing Date (as defined below) and the completion of the Underwriters'
distribution of the Shares, any offering material in connection with the
offering and sale of the Shares other than a preliminary prospectus, the
Prospectus or the Registration Statement.

         (d)      The Underwriting Agreement. This Agreement has been duly
authorized, executed and delivered by, and is a valid and binding agreement of,
the Company, enforceable in accordance with its terms, except as rights to
indemnification hereunder may be limited by applicable law and except as the
enforcement hereof may be limited by bankruptcy, insolvency, reorganization,
moratorium or other similar laws relating to or affecting the rights and
remedies of creditors or by general equitable principles.

         (e)      Authorization of the Shares. The Shares to be purchased by the
Underwriters from the Company have been duly authorized for issuance and sale
pursuant to this Agreement and, when issued and delivered by the Company
pursuant to this Agreement, will be validly issued, fully paid and
nonassessable.

         (f)      No Applicable Registration or Other Similar Rights. There are
no persons with registration or other similar rights to have any equity or debt
securities registered for sale under the Registration Statement or included in
the offering contemplated by this Agreement, except for such rights as have been
duly waived.

         (g)      No Material Adverse Change. Subsequent to the respective dates
as of which information is given in the Prospectus: (i) there has been no
material adverse change, or any development that could reasonably be expected to
result in a material adverse change, in the condition, financial or otherwise,
or in the earnings, business, operations or prospects, whether or not arising
from transactions in the ordinary course of business, of the Company and its
subsidiaries, considered as one entity (any such change or effect, where the
context so requires, is called a "Material Adverse Change" or a "Material
Adverse Effect"); (ii) the Company and its subsidiaries, considered as one
entity, have not incurred any material liability or obligation, indirect, direct
or contingent, not in the ordinary course of business nor entered into any
material transaction or agreement not in the ordinary course of business; and
(iii) except for dividends paid in connection with the adoption by the Company
in September 2000 of a new shareholders rights plan, there has been no dividend
or distribution of any kind declared, paid or made by the Company or, except for
dividends paid to the Company or other subsidiaries, any of its subsidiaries on
any class of capital stock or repurchase or redemption by the Company or any of
its subsidiaries of any class of capital stock.


                                       3.
<PAGE>   4

         (h)      Independent Accountants. KPMG LLC, who have expressed their
opinion with respect to the financial statements (which term as used in this
Agreement includes the related notes thereto) and supporting schedules filed
with the Commission as a part of the Registration Statement and included in the
Prospectus, are independent public or certified public accountants as required
by the Securities Act and the Exchange Act.

         (i)      Preparation of the Financial Statements. The financial
statements filed with the Commission as a part of the Registration Statement and
included in the Prospectus present fairly the consolidated financial position of
the Company and its subsidiaries as of and at the dates indicated and the
results of their operations and cash flows for the periods specified. The
supporting schedules included in the Registration Statement present fairly the
information required to be stated therein. Such financial statements and
supporting schedules have been prepared in conformity with generally accepted
accounting principles as applied in the United States applied on a consistent
basis throughout the periods involved, except as may be expressly stated in the
related notes thereto. No other financial statements or supporting schedules are
required to be included in the Registration Statement. The financial data set
forth in the Prospectus under the captions "Summary--Summary Consolidated
Financial Data", "Selected Consolidated Financial Data" and "Capitalization"
fairly present the information set forth therein on a basis consistent with that
of the audited financial statements contained in the Registration Statement. The
pro forma consolidated financial statements of the Company and its subsidiaries
and the related notes thereto included under the caption "Prospectus Summary
Summary Consolidated Financial Data", "Selected Consolidated Financial Data" and
elsewhere in the Prospectus and in the Registration Statement present fairly the
information contained therein, have been prepared in accordance with the
Commission's rules and guidelines with respect to pro forma financial statements
and have been properly presented on the bases described therein, and the
assumptions used in the preparation thereof are reasonable and the adjustments
used therein are appropriate to give effect to the transactions and
circumstances referred to therein. No other pro forma financial information is
required to be included in the Registration Statement Pursuant to Regulation
S-X.

         (j)      Company's Accounting System. The Company and each of its
subsidiaries maintain a system of accounting controls sufficient to provide
reasonable assurances that (i) transactions are executed in accordance with
management's general or specific authorization; (ii) transactions are recorded
as necessary to permit preparation of financial statements in conformity with
generally accepted accounting principles as applied in the United States and to
maintain accountability for assets; (iii) access to assets is permitted only in
accordance with management's general or specific authorization; and (iv) the
recorded accountability for assets is compared with existing assets at
reasonable intervals and appropriate action is taken with respect to any
differences.

         (k)      Subsidiaries of the Company. The Company does not own or
control, directly or indirectly, any corporation, association or other entity
other than the subsidiaries listed in Exhibit 21 to the Registration Statement

         (l)      Incorporation and Good Standing of the Company and its
Subsidiaries. Each of the Company and its subsidiaries has been duly organized
and is validly existing as a corporation in good standing under the laws of the
jurisdiction in which it is organized with full corporate power and authority to
own its properties and conduct its business as described in the prospectus, and
is duly qualified to do business as a foreign corporation and is in good
standing under the laws of each jurisdiction which requires such qualification.


                                       4.
<PAGE>   5

         (m)      Capitalization of the Subsidiaries. All the outstanding shares
of capital stock of each subsidiary have been duly and validly authorized and
issued and are fully paid and nonassessable, and, except as otherwise set forth
in the Prospectus, all outstanding shares of capital stock of the subsidiaries
are owned by the Company either directly or through wholly owned subsidiaries
free and clear of any security interests, claims, liens or encumbrances.

         (n)      No Prohibition on Subsidiaries from Paying Dividends or Making
Other Distributions. No subsidiary of the Company is currently prohibited,
directly or indirectly, from paying any dividends to the Company, from making
any other distribution on such subsidiary's capital stock, from repaying to the
Company any loans or advances to such subsidiary from the Company or from
transferring any of such subsidiary's property or assets to the Company or any
other subsidiary of the Company, except as described in or contemplated by the
Prospectus.

         (o)      Capitalization and Other Capital Stock Matters. The
authorized, issued and outstanding capital stock of the Company is as set forth
in the Prospectus under the caption "Capitalization" (other than for subsequent
issuances, if any, pursuant to employee benefit plans described in the
Prospectus or upon exercise of outstanding options [or warrants] described in
the Prospectus). The Common Shares (including the Shares) conform in all
material respects to the description thereof contained in the Prospectus. All of
the issued and outstanding Common Shares have been duly authorized and validly
issued, are fully paid and nonassessable and have been issued in compliance with
federal and state securities laws. None of the outstanding Common Shares were
issued in violation of any preemptive rights, rights of first refusal or other
similar rights to subscribe for or purchase securities of the Company. There are
no authorized or outstanding options, warrants, preemptive rights, rights of
first refusal or other rights to purchase, or equity or debt securities
convertible into or exchangeable or exercisable for, any capital stock of the
Company or any of its subsidiaries other than those accurately described in the
Prospectus. The description of the Company's stock option, stock bonus and other
stock plans or arrangements, and the options or other rights granted thereunder,
set forth in the Prospectus accurately and fairly presents the information
required to be shown with respect to such plans, arrangements, options and
rights.

         (p)      Stock Exchange Listing. The Shares are registered pursuant to
Section 12(b) or 12(g) of the Exchange Act and are listed on the Nasdaq National
Market, and the Company has taken no action designed to, or likely to have the
effect of, terminating the registration of the Common Shares under the Exchange
Act or delisting the Common Shares from the Nasdaq national, nor has the Company
received any notification that the Commission or the National Association of
Securities Dealers, LLC (the "NASD") is contemplating terminating such
registration or listing.

         (q)      No Consents, Approvals or Authorizations Required. No consent,
approval, authorization, filing with or order of any court or governmental
agency or regulatory body is required in connection with the transactions
contemplated herein, except such as have been obtained or made under the
Securities Act and such as may be required (i) under the blue sky laws of any
jurisdiction in connection with the purchase and distribution of the Shares by
the Underwriters in the manner contemplated herein and in the Prospectus, (ii)
by the National Association of Securities Dealers, LLC and (iii) by the federal
and provincial laws of Canada.

         (r)      Non-Contravention of Existing Instruments Agreements. Neither
the issue and sale of the Shares nor the consummation of any other of the
transactions herein contemplated nor the fulfillment of the terms hereof will
conflict with, result in a breach or violation or


                                       5.
<PAGE>   6

imposition of any lien, charge or encumbrance upon any property or assets of the
Company or any of its subsidiaries pursuant to, (i) the charter or by-laws of
the Company or any of its subsidiaries, (ii) the terms of any indenture,
contract, lease, mortgage, deed of trust, note agreement, loan agreement or
other agreement, obligation, condition, covenant or instrument to which the
Company or any of its subsidiaries is a party or bound or to which its or their
property is subject or (iii) any statute, law, rule, regulation, judgment, order
or decree applicable to the Company or any of its subsidiaries of any court,
regulatory body, administrative agency, governmental body, arbitrator or other
authority having jurisdiction over the Company or any of its subsidiaries or any
of its or their properties.

         (s)      No Defaults or Violations. Neither the Company nor any
subsidiary is in violation or default of (i) any provision of its charter or
by-laws, (ii) the terms of any indenture, contract, lease, mortgage, deed of
trust, note agreement, loan agreement or other agreement, obligation, condition,
covenant or instrument to which it is a party or bound or to which its property
is subject or (iii) any statute, law, rule, regulation, judgment, order or
decree of any court, regulatory body, administrative agency, governmental body,
arbitrator or other authority having jurisdiction over the Company or such
subsidiary or any of its properties, as applicable, except any such violation or
default which would not, singly or in the aggregate, result in a Material
Adverse Change except as otherwise disclosed in the Prospectus.

         (t)      No Actions, Suits or Proceedings. No action, suit or
proceeding by or before any court or governmental agency, authority or body or
any arbitrator involving the Company or any of its subsidiaries or its or their
property is pending or, to the best knowledge of the Company, threatened that
(i) could reasonably be expected to have a Material Adverse Effect on the
performance of this Agreement or the consummation of any of the transactions
contemplated hereby or (ii) could reasonably be expected to result in a Material
Adverse Effect.

         (u)      All Necessary Permits, Etc. The Company and each subsidiary
possess such valid and current certificates, authorizations or permits issued by
the appropriate state, federal or foreign regulatory agencies or bodies
necessary to conduct their respective businesses, and neither the Company nor
any subsidiary has received any notice of proceedings relating to the revocation
or modification of, or non-compliance with, any such certificate, authorization
or permit which, singly or in the aggregate, if the subject of an unfavorable
decision, ruling or finding, could result in a Material Adverse Change.

         (v)      Title to Properties. The Company and each of its subsidiaries
has good and marketable title to all the properties and assets reflected as
owned in the financial statements referred to in Section 1(i) above in each case
free and clear of any security interests, mortgages, liens, encumbrances,
equities, claims and other defects, except such as do not materially and
adversely affect the value of such property and do not materially interfere with
the use made or proposed to be made of such property by the Company or such
subsidiary. The real property, improvements, equipment and personal property
held under lease by the Company or any subsidiary are held under valid and
enforceable leases, with such exceptions as are not material and do not
materially interfere with the use made or proposed to be made of such real
property, improvements, equipment or personal property by the Company or such
subsidiary.

         (w)      Tax Law Compliance. The Company and its consolidated
subsidiaries have filed all necessary federal, state and foreign income and
franchise tax returns and have paid all taxes required to be paid by any of them
and, if due and payable, any related or similar assessment, fine or penalty
levied against any of them. The Company has made adequate charges, accruals


                                       6.
<PAGE>   7

and reserves in the applicable financial statements referred to in Section 1(i)
above in respect of all federal, state and foreign income and franchise taxes
for all periods as to which the tax liability of the Company or any of its
consolidated subsidiaries has not been finally determined. The Company is not
aware of any tax deficiency that has been or might be asserted or threatened
against the Company that could result in a Material Adverse Change.

         (x)      Intellectual Property Rights. Each of the Company and its
subsidiaries owns or possesses adequate rights to use all patents, patent rights
or licenses, inventions, collaborative research agreements, trade secrets,
know-how, trademarks, service marks, trade names and copyrights which are
necessary to conduct its businesses as described in the Registration Statement
and Prospectus; the expiration of any patents, patent rights, trade secrets,
trademarks, service marks, trade names or copyrights would not result in a
Material Adverse Change that is not otherwise disclosed in the Prospectus; the
Company has not received any notice of, and has no knowledge of, any
infringement of or conflict with asserted rights of the Company by others with
respect to any patent, patent rights, inventions, trade secrets, know-how,
trademarks, service marks, trade names or copyrights; and the Company has not
received any notice of, and has no knowledge of, any infringement of or conflict
with asserted rights of others with respect to any patent, patent rights,
inventions, trade secrets, know-how, trademarks, service marks, trade names or
copyrights which, singly or in the aggregate, if the subject of an unfavorable
decision, ruling or finding, might have a Material Adverse Change. There is no
claim being made against the Company regarding patents, patent rights or
licenses, inventions, collaborative research, trade secrets, know-how,
trademarks, service marks, trade names or copyrights. The Company and its
subsidiaries do not in the conduct of their business as now or proposed to be
conducted as described in the Prospectus infringe or conflict with any right or
patent of any third party, or any discovery, invention, product or process which
is the subject of a patent application filed by any third party, known to the
Company or any of its subsidiaries, which such infringement or conflict is
reasonably likely to result in a Material Adverse Change.

         (y)      Y2K. There are no Y2K issues related to the Company, or any of
its subsidiaries, that (i) are of a character required to be described or
referred to in the Registration Statement or Prospectus by the Securities Act or
by the Exchange Act or the rules and regulations of the Commission thereunder
which have not been accurately described in the Registration Statement or
Prospectus or (ii) might reasonably be expected to result in any Material
Adverse Change or that might materially affect their properties, assets or
rights.

         (z)      No Transfer Taxes or Other Fees. There are no transfer taxes
or other similar fees or charges under Federal law or the laws of any state, or
any political subdivision thereof, required to be paid in connection with the
execution and delivery of this Agreement or the issuance and sale by the Company
of the Shares.

         (aa)     Company Not an "Investment Company". The Company has been
advised of the rules and requirements under the Investment Company Act of 1940,
as amended (the "Investment Company Act"). The Company is not, and after receipt
of payment for the Shares will not be, an "investment company" or an entity
"controlled" by an "investment company" within the meaning of the Investment
Company Act and will conduct its business in a manner so that it will not become
subject to the Investment Company Act.

         (bb)     Insurance. Each of the Company and its subsidiaries are
insured by recognized, financially sound and reputable institutions with
policies in such amounts and with such deductibles and covering such risks as
are generally deemed adequate and customary for their


                                       7.
<PAGE>   8

businesses including, but not limited to, policies covering real and personal
property owned or leased by the Company and its subsidiaries against theft,
damage, destruction, acts of vandalism and earthquakes, general liability and
Directors and Officers liability. The Company has no reason to believe that it
or any subsidiary will not be able (i) to renew its existing insurance coverage
as and when such policies expire or (ii) to obtain comparable coverage from
similar institutions as may be necessary or appropriate to conduct its business
as now conducted and at a cost that would not result in a Material Adverse
Change. Neither of the Company nor any subsidiary has been denied any insurance
coverage which it has sought or for which it has applied.

         (cc)     Labor Matters. To the best of Company's knowledge, no labor
disturbance by the employees of the Company or any of its subsidiaries exists or
is imminent; and the Company is not aware of any existing or imminent labor
disturbance by the employees of any of its principal suppliers, original
equipment manufacturers, or research collaborators that might be expected to
result in a Material Adverse Change.

         (dd)     No Price Stabilization or Manipulation. The Company has not
taken and will not take, directly or indirectly, any action designed to or that
might be reasonably expected to cause or result in stabilization or manipulation
of the price of the Common Stock to facilitate the sale or resale of the Shares.

         (ee)     Lock-Up Agreements. Each officer and director of the company
has signed an agreement substantially in the form attached hereto as Exhibit A
(the "Lock-up Agreements"). The Company has provided to counsel for the
Underwriters a complete and accurate list of all securityholders of the Company
and the number and type of securities held by each securityholder. The Company
has provided to counsel for the Underwriters true, accurate and complete copies
of all of the Lock-up Agreements presently in effect or effected hereby. The
Company hereby represents and warrants that it will not release any of its
officers, directors or other stockholders from any Lock-up Agreements currently
existing or hereafter effected without the prior written consent of Robertson
Stephens.

         (ff)     Related Party Transactions. There are no business
relationships or related-party transactions involving the Company or any
subsidiary or any other person required to be described in the Prospectus which
have not been described as required.

         (gg)     No Unlawful Contributions or Other Payments. Neither the
Company nor any of its subsidiaries nor, to the best of the Company's knowledge,
any employee or agent of the Company or any subsidiary, has made any
contribution or other payment to any official of, or candidate for, any federal,
state or foreign office in violation of any law or of the character required to
be disclosed in the Prospectus.

         (hh)     Environmental Laws. (i) 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 where the failure to comply
would not result in a Material Adverse Change, (ii) the Company has received no
notice from any governmental authority or third party of an asserted claim under
Environmental Laws, which claim is required to be disclosed in the Registration
Statement and the Prospectus, (iii) the Company is not currently aware that it
will be required to make future material capital expenditures to comply with
Environmental Laws and (iv) no property which is owned, leased or occupied by
the Company has been designated as a Superfund site pursuant to the
Comprehensive Response, Compensation, and Liability Act


                                       8.
<PAGE>   9

of 1980, as amended (42 U.S.C. ss. 9601, et seq.), or otherwise designated as a
contaminated site under applicable state or local law.

         (ii)     Periodic Review of Costs of Environmental Compliance. In the
ordinary course of its business, the Company conducts a periodic review of the
effect of Environmental Laws on the business, operations and properties of the
Company and its subsidiaries, in the course of which it identifies and evaluates
associated costs and liabilities (including, without limitation, any capital or
operating expenditures required for clean-up, closure of properties or
compliance with Environmental Laws or any permit, license or approval, any
related constraints on operating activities and any potential liabilities to
third parties). On the basis of such review and the amount of its established
reserves, the Company has reasonably concluded that such associated costs and
liabilities would not, individually or in the aggregate, result in a Material
Adverse Change.

         (jj)     ERISA Compliance. The Company and its subsidiaries and any
"employee benefit plan" (as defined under the Employee Retirement Income
Security Act of 1974, as amended, and the regulations and published
interpretations thereunder (collectively, "ERISA")) established or maintained by
the Company, its subsidiaries or their "ERISA Affiliates" (as defined below) are
in compliance in all material respects with ERISA. "ERISA Affiliate" means, with
respect to the Company or a subsidiary, any member of any group of organizations
described in Sections 414(b),(c),(m) or (o) of the Internal Revenue Code of
1986, as amended, and the regulations and published interpretations thereunder
(the "Code") of which the Company or such subsidiary is a member. No "reportable
event" (as defined under ERISA) has occurred or is reasonably expected to occur
with respect to any "employee benefit plan" established or maintained by the
Company, its subsidiaries or any of their ERISA Affiliates. No "employee benefit
plan" established or maintained by the Company, its subsidiaries or any of their
ERISA Affiliates, if such "employee benefit plan" were terminated, would have
any "amount of unfunded benefit liabilities" (as defined under ERISA) that
reasonably could be expected to result in a Material Adverse Change. Neither the
Company, its subsidiaries nor any of their ERISA Affiliates has incurred or
reasonably expects to incur any liability under (i) Title IV of ERISA with
respect to termination of, or withdrawal from, any "employee benefit plan" or
(ii) Sections 412, 4971, 4975 or 4980B of the Code. Each "employee benefit plan"
established or maintained by the Company, its subsidiaries or any of their ERISA
Affiliates that is intended to be qualified under Section 401(a) of the Code is
so qualified and nothing has occurred, whether by action or failure to act,
which would cause the loss of such qualification.

         (kk)     Exchange Act Compliance. The documents incorporated or deemed
to be incorporated by reference in the Prospectus, at the time they were or
hereafter are filed with the Commission, complied and will comply in all
material respects with the requirements of the Exchange Act, and, when read
together with the other information in the Prospectus, at the time the
Registration Statement and any amendments thereto become effective and at the
First Closing Date and the Second Closing Date, as the case may be, 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 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.

         (ll)     Exchange Act Reports Filed. The Company has filed all reports
required to be filed pursuant to the Securities Act and the Exchange Act.


                                       9.
<PAGE>   10

         (mm)     Conditions for Use of Form S-3. The Company has satisfied the
conditions for the use of Form S-3, as set forth in the general instructions
thereto, with respect to the Registration Statement.

Any certificate signed by an officer of the Company and delivered to the
Representatives or to counsel for the Underwriters shall be deemed to be a
representation and warranty by the Company to each Underwriter as to the matters
set forth therein.

         SECTION 2.        PURCHASE, SALE AND DELIVERY OF THE SHARES.

         (a)      The Firm Shares. The Company agrees to issue and sell to the
several Underwriters the Firm Shares upon the terms herein set forth. On the
basis of the representations, warranties and agreements herein contained, and
upon the terms but subject to the conditions herein set forth, the Underwriters
agree, severally and not jointly, to purchase from the Company the respective
number of Firm Shares set forth opposite their names on Schedule A. The purchase
price per Firm Share to be paid by the several Underwriters to the Company shall
be $[___] per share.

         (b)      The First Closing Date. Delivery of the Firm Shares to be
purchased by the Underwriters and payment therefor shall be made by the Company
and the Representatives at 6:00 a.m. San Francisco time, at the offices of
Robertson Stephens (or such other place as may be agreed upon among the
Representatives and the Company), (i) on the third (3rd) full business day
following the first day that Shares are traded, (ii) if this Agreement is
executed and delivered after 1:30 P.M., San Francisco time, the fourth (4th)
full business day following the day that this Agreement is executed and
delivered or (iii) at such other time and date not later that seven (7) full
business days following the first day that Shares are traded as the
Representatives and the Company may determine (or at such time and date to which
payment and delivery shall have been postponed pursuant to Section 8 hereof),
such time and date of payment and delivery being herein called the "Closing
Date;" provided, however, that if the Company has not made available to the
Representatives copies of the Prospectus within the time provided in Section
2(g) and 3(e) hereof, the Representatives may, in their sole discretion,
postpone the Closing Date until no later that two (2) full business days
following delivery of copies of the Prospectus to the Representatives.

         (c)      The Option Shares; the Second Closing Date. In addition, on
the basis of the representations, warranties and agreements herein contained,
and upon the terms but subject to the conditions herein set forth, the Company
hereby grants an option to the several Underwriters to purchase, severally and
not jointly, up to an aggregate of 675,000 Option Shares from the Company at the
purchase price per share to be paid by the Underwriters for the Firm Shares. The
option granted hereunder is for use by the Underwriters solely in covering any
over-allotments in connection with the sale and distribution of the Firm Shares.
The option granted hereunder may be exercised at any time upon notice by the
Representatives to the Company, which notice may be given at any time within 30
days from the date of this Agreement. The time and date of delivery of the
Option Shares, if subsequent to the First Closing Date, is called the "Second
Closing Date" and shall be determined by the Representatives and shall not be
earlier than three nor later than five full business days after delivery of such
notice of exercise. If any Option Shares are to be purchased, each Underwriter
agrees, severally and not jointly, to purchase the number of Option Shares
(subject to such adjustments to eliminate fractional shares as the
Representatives may determine) that bears the


                                       10.
<PAGE>   11

same proportion to the total number of Option Shares to be purchased as the
number of Firm Shares set forth on Schedule A opposite the name of such
Underwriter bears to the total number of Firm Shares. The Representatives may
cancel the option at any time prior to its expiration by giving written notice
of such cancellation to the Company.

         (d)      Public Offering of the Shares. The Representatives hereby
advise the Company that the Underwriters intend to offer for sale to the public,
as described in the Prospectus, their respective portions of the Shares as soon
after this Agreement has been executed and the Registration Statement has been
declared effective as the Representatives, in their sole judgment, have
determined is advisable and practicable.

         (e)      Payment for the Shares. Payment for the Shares shall be made
at the First Closing Date (and, if applicable, at the Second Closing Date) by
wire transfer in immediately available-funds to the order of the Company.

                  It is understood that the Representatives have been
authorized, for their own accounts and the accounts of the several Underwriters,
to accept delivery of and receipt for, and make payment of the purchase price
for, the Firm Shares and any Option Shares the Underwriters have agreed to
purchase. Robertson Stephens, individually and not as a Representative of the
Underwriters, may (but shall not be obligated to) make payment for any Shares to
be purchased by any Underwriter whose funds shall not have been received by the
Representatives by the First Closing Date or the Second Closing Date, as the
case may be, for the account of such Underwriter, but any such payment shall not
relieve such Underwriter from any of its obligations under this Agreement.

         (f)      Delivery of the Shares. The Company shall deliver, or cause to
be delivered, a credit representing the Firm Shares to an account or accounts at
The Depository Trust Company, as designated by the Representatives for the
accounts of the Representatives and the several Underwriters at the First
Closing Date, against the irrevocable release of a wire transfer of immediately
available funds for the amount of the purchase price therefor. The Company shall
also deliver, or cause to be delivered, a credit representing the Option Shares
the Underwriters have agreed to purchase at the First Closing Date (or the
Second Closing Date, as the case may be), to an account or accounts at The
Depository Trust Company as designated by the Representatives for the accounts
of the Representatives and the several Underwriters, against the irrevocable
release of a wire transfer of immediately available funds for the amount of the
purchase price therefor. Time shall be of the essence, and delivery at the time
and place specified in this Agreement is a further condition to the obligations
of the Underwriters.

         (g)      Delivery of Prospectus to the Underwriters. Not later than
12:00 noon on the second business day following the date the Shares are released
by the Underwriters for sale to the public, the Company shall deliver or cause
to be delivered copies of the Prospectus in such quantities and at such places
as the Representatives shall request.

         SECTION 3.        COVENANTS OF THE COMPANY.

                  The Company further covenants and agrees with each Underwriter
as follows:

         (a)      Registration Statement Matters. The Company will (i) use its
best efforts to cause the Registration Statement to become effective or, if the
procedure in Rule 430A of the Securities Act is followed, to prepare and timely
file with the Commission under Rule 424(b)


                                       11.
<PAGE>   12

under the Securities Act a Prospectus in a form approved by the Representatives
containing information previously omitted at the time of effectiveness of the
Registration Statement in reliance on Rule 430A of the Securities Act and (ii)
not file any amendment to the Registration Statement or supplement to the
Prospectus of which the Representatives shall not previously have been advised
and furnished with a copy or to which the Representatives shall have reasonably
objected in writing or which is not in compliance with the Securities Act. If
the Company elects to rely on Rule 462(b) under the Securities Act, the Company
shall file a Rule 462(b) Registration Statement with the Commission in
compliance with Rule 462(b) under the Securities Act prior to the time
confirmations are sent or given, as specified by Rule 462(b)(2) under the
Securities Act, and shall pay the applicable fees in accordance with Rule 111
under the Securities Act.

         (b)      Securities Act Compliance. The Company will advise the
Representatives promptly (i) when the Registration Statement or any
post-effective amendment thereto shall have become effective, (ii) of receipt of
any comments from the Commission, (iii) of any request of the Commission for
amendment of the Registration Statement or for supplement to the Prospectus or
for any additional information and (iv) of the issuance by the Commission of any
stop order suspending the effectiveness of the Registration Statement or the use
of the Prospectus or of the institution of any proceedings for that purpose. The
Company will use its best efforts to prevent the issuance of any such stop order
preventing or suspending the use of the Prospectus and to obtain as soon as
possible the lifting thereof, if issued.

         (c)      Blue Sky Compliance. The Company will cooperate with the
Representatives and counsel for the Underwriters in endeavoring to qualify the
Shares for sale under the securities laws of such jurisdictions (both national
and foreign) as the Representatives may reasonably have designated in writing
and will make such applications, file such documents, and furnish such
information as may be reasonably required for that purpose, provided the Company
shall not be required to qualify as a foreign corporation or to file a general
consent to service of process in any jurisdiction where it is not now so
qualified or required to file such a consent. The Company will, from time to
time, prepare and file such statements, reports and other documents, as are or
may be required to continue such qualifications in effect for so long a period
as the Representatives may reasonably request for distribution of the Shares.

         (d)      Amendments and Supplements to the Prospectus and Other
Securities Act Matters. The Company will comply with the Securities Act and the
Exchange Act, and the rules and regulations of the Commission thereunder, so as
to permit the completion of the distribution of the Shares as contemplated in
this Agreement and the Prospectus. If during the period in which a prospectus is
required by law to be delivered by an Underwriter or dealer, any event shall
occur as a result of which, in the judgment of the Company or in the reasonable
opinion of the Representatives or counsel for the Underwriters, it becomes
necessary to amend or supplement the Prospectus in order to make the statements
therein, in the light of the circumstances existing at the time the Prospectus
is delivered to a purchaser, not misleading, or, if it is necessary at any time
to amend or supplement the Prospectus to comply with any law, the Company
promptly will prepare and file with the Commission, and furnish at its own
expense to the Underwriters and to dealers, an appropriate amendment to the
Registration Statement or supplement to the Prospectus so that the Prospectus as
so amended or supplemented will not, in the light of the circumstances when it
is so delivered, be misleading, or so that the Prospectus will comply with the
law.

         (e)      Copies of any Amendments and Supplements to the Prospectus.
The Company agrees to furnish to the Representatives, without charge, during the
period beginning on the


                                       12.
<PAGE>   13

date hereof and ending on the later of the First Closing Date or such date, as
in the opinion of counsel for the Underwriters, the Prospectus is no longer
required by law to be delivered in connection with sales by an Underwriter or
dealer (the "Prospectus Delivery Period"), as many copies of the Prospectus and
any amendments and supplements thereto (including any documents incorporated or
deemed incorporated by reference therein) as the Representatives may reasonably
request.

         (f)      Insurance. The Company shall have or obtain Directors and
Officers liability insurance in the minimum amount of $10 million which shall
apply to the offering contemplated hereby.

         (g)      Notice of Subsequent Events. If at any time during the ninety
(90) day period after the Registration Statement becomes effective, any rumor,
publication or event relating to or affecting the Company shall occur as a
result of which, in your opinion, the market price of the Common Shares has been
or is likely to be materially affected (regardless of whether such rumor,
publication or event necessitates a supplement to or amendment of the
Prospectus), the Company will, after written notice from you advising the
Company to the effect set forth above, forthwith prepare, consult with you
concerning the substance of and disseminate a press release or other public
statement, reasonably satisfactory to you, responding to or commenting on such
rumor, publication or event.

         (h)      Use of Proceeds. The Company shall apply the net proceeds from
the sale of the Shares in the manner described under the caption "Use of
Proceeds" in the Prospectus.

         (i)      Transfer Agent. The Company shall engage and maintain, at its
expense, a registrar and transfer agent for the Common Shares.

         (j)      Earnings Statement. As soon as practicable, the Company will
make generally available to its security holders and to the Representatives an
earnings statement (which need not be audited) covering the twelve-month period
ending December 31, 2001 that satisfies the provisions of Section 11(a) of the
Securities Act.

         (k)      Periodic Reporting Obligations. During the Prospectus Delivery
Period the Company shall file, on a timely basis, with the Commission and the
Nasdaq National Market all reports and documents required to be filed under the
Exchange Act.

         (l)      Agreement Not to Offer or Sell Additional Securities. The
Company will not offer, sell or contract to sell, or otherwise dispose of or
enter into any transaction which is designed to, or could be expected to, result
in the disposition (whether by actual disposition or effective economic
disposition due to cash settlement or otherwise by the Company or any affiliate
of the Company or any person in privity with the Company or any affiliate of the
Company) directly or indirectly, or announce the offering of, any other Common
Shares or any securities convertible into, or exchangeable for, Common Shares;
provided, however, that the Company may (i) issue and sell Common Shares
pursuant to any director or employee stock option plan, stock ownership plan or
dividend reinvestment plan of the Company in effect at the date of the
Prospectus and (ii) the Company may issue Common Shares issuable upon the
conversion of securities or the exercise of warrants outstanding at the date of
the Prospectus and described in the Prospectus. These restrictions terminate
after the close of trading of the Shares on the 90th day of (and including) the
day the Shares commenced trading on the Nasdaq National Market (the "Lock-Up
Period").



                                       13.
<PAGE>   14

         (m)      Future Reports to the Representatives. During the period of
five years hereafter the Company will furnish to the Representatives (i) as soon
as practicable after the end of each fiscal year, copies of the Annual Report of
the Company containing the balance sheet of the Company as of the close of such
fiscal year and statements of income, stockholders' equity and cash flows for
the year then ended and the opinion thereon of the Company's independent public
or certified public accountants; (ii) as soon as practicable after the filing
thereof, copies of each proxy statement, Annual Report on Form 10-K, Quarterly
Report on Form 10-Q, Current Report on Form 8-K or other report filed by the
Company with the Commission, the National Association of Securities Dealers, LLC
or any securities exchange; and (iii) as soon as available, copies of any report
or communication of the Company mailed generally to holders of its capital
stock.

         (n)      Exchange Act Compliance. During the Prospectus Delivery
Period, the Company will file all documents required to be filed with the
Commission pursuant to Section 13, 14 or 15 of the Exchange Act in the manner
and within the time periods required by the Exchange Act.

         SECTION 4.        CONDITIONS OF THE OBLIGATIONS OF THE UNDERWRITERS.
The obligations of the several Underwriters to purchase and pay for the Shares
as provided herein on the First Closing Date and, with respect to the Option
Shares, the Second Closing Date, shall be subject to the accuracy of the
representations and warranties on the part of the Company set forth in Section 1
hereof as of the date hereof and as of the First Closing Date as though then
made and, with respect to the Option Shares, as of the Second Closing Date as
though then made, to the timely performance by the Company of its covenants and
other obligations hereunder, and to each of the following additional conditions:

         (a)      Compliance with Registration Requirements; No Stop Order; No
Objection from the National Association of Securities Dealers, LLC. The
Registration Statement shall have become effective prior to the execution of
this Agreement, or at such later date as shall be consented to in writing by
you; and no stop order suspending the effectiveness thereof shall have been
issued and no proceedings for that purpose shall have been initiated or, to the
knowledge of the Company or any Underwriter, threatened by the Commission, and
any request of the Commission for additional information (to be included in the
Registration Statement or the Prospectus or any Incorporated Document or
otherwise) shall have been complied with to the satisfaction of Underwriters'
Counsel; and the NASD shall have raised no objection to the fairness and
reasonableness of the underwriting terms and arrangements.

         (b)      Corporate Proceedings. All corporate proceedings and other
legal matters in connection with this Agreement, the form of Registration
Statement and the Prospectus, and the registration, authorization, issue, sale
and delivery of the Shares, shall have been reasonably satisfactory to
Underwriters' Counsel, and such counsel shall have been furnished with such
papers and information as they may reasonably have requested to enable them to
pass upon the matters referred to in this Section.

         (c)      No Material Adverse Change. Subsequent to the execution and
delivery of this Agreement and prior to the First Closing Date, or the Second
Closing Date, as the case may be, there shall not have been any Material Adverse
Change in the condition (financial or otherwise), earnings, operations, business
or business prospects of the Company and its subsidiaries considered as one
enterprise from that set forth in the Registration Statement or Prospectus,
which, in your sole judgment, is material and adverse and that makes it, in your
sole judgment, impracticable or inadvisable to proceed with the public offering
of the Shares as contemplated by the Prospectus.


                                       14.
<PAGE>   15

         (d)      Opinion of Counsel for the Company. You shall have received on
the First Closing Date, or the Second Closing Date, as the case may be, an
opinion of Saul Ewing LLP, counsel for the Company, substantially in the form of
Exhibit B attached hereto, dated the First Closing Date, or the Second Closing
Date, addressed to the Underwriters and with reproduced copies or signed
counterparts thereof for each of the Underwriters.

                  Counsel rendering the opinion contained in Exhibit B may rely
as to questions of law not involving the laws of the United States or the States
of New York or Delaware upon opinions of local counsel, and as to questions of
fact upon representations or certificates of officers of the Company and of
government officials, in which case their opinion is to state that they are so
relying and that they have no knowledge of any material misstatement or
inaccuracy in any such opinion, representation or certificate. Copies of any
opinion, representation or certificate so relied upon shall be delivered to you,
as Representatives of the Underwriters, and to Underwriters' Counsel.

         (e)      Opinion of Intellectual Property Counsel for the Company. You
shall have received on the First Closing Date, or the Second Closing Date, as
the case may be, an opinion of Cooper & Dunham, LLP, intellectual property
counsel for the Company, substantially in the form of Exhibit C attached hereto.

         (f)      Opinion of Counsel for the Underwriters. You shall have
received on the First Closing Date or the Second Closing Date, as the case may
be, an opinion of Testa, Hurwitz & Thibeault, LLP, substantially in the form of
Exhibit D hereto. The Company shall have furnished to such counsel such
documents as they may have requested for the purpose of enabling them to pass
upon such matters.

         (g)      Accountants' Comfort Letter. You shall have received on the
First Closing Date and on the Second Closing Date, as the case may be, a letter
from KPMG LLP addressed to the Underwriters, dated the First Closing Date or the
Second Closing Date, as the case may be, confirming that they are independent
certified public accountants with respect to the Company within the meaning of
the Act and the applicable published Rules and Regulations and based upon the
procedures described in such letter delivered to you concurrently with the
execution of this Agreement (herein called the "Original Letter"), but carried
out to a date not more than four (4) business days prior to the First Closing
Date or the Second Closing Date, as the case may be, (i) confirming, to the
extent true, that the statements and conclusions set forth in the Original
Letter are accurate as of the First Closing Date or the Second Closing Date, as
the case may be, and (ii) setting forth any revisions and additions to the
statements and conclusions set forth in the Original Letter which are necessary
to reflect any changes in the facts described in the Original Letter since the
date of such letter, or to reflect the availability of more recent financial
statements, data or information. The letter shall not disclose any change in the
condition (financial or otherwise), earnings, operations, business or business
prospects of the Company and its subsidiaries considered as one enterprise from
that set forth in the Registration Statement or Prospectus, which, in your sole
judgment, is material and adverse and that makes it, in your sole judgment,
impracticable or inadvisable to proceed with the public offering of the Shares
as contemplated by the Prospectus. The Original Letter from KPMG LLP shall be
addressed to or for the use of the Underwriters in form and substance
satisfactory to the Underwriters and shall (i) represent, to the extent true,
that they are independent certified public accountants with respect to the
Company within the meaning of the Act and the applicable published Rules and
Regulations, (ii) set forth their opinion with respect to their examination of
the consolidated balance sheets of the Company as of September 30, 1999 and
related consolidated statements of operations, shareholders' equity, and cash
flows for the twelve


                                       15.
<PAGE>   16

(12) months ended September 30, 1999, (iii) state that KPMG LLP has performed
the procedures set out in Statement on Auditing Standards No. 71 ("SAS 71") for
a review of interim financial information and providing the report of KPMG LLP
as described in SAS 71 on the financial statements for each of the quarters in
the three-quarter period ended June 30, 2000 (the "Quarterly Financial
Statements"), (iv) state that in the course of such review, nothing came to
their attention that leads them to believe that any material modifications need
to be made to any of the Quarterly Financial Statements in order for them to be
in compliance with generally accepted accounting principles consistently applied
across the periods presented, and address other matters agreed upon by KPMG LLP
and you. In addition, you shall have received from KPMG LLP a letter addressed
to the Company and made available to you for the use of the Underwriters stating
that their review of the Company's system of internal accounting controls, to
the extent they deemed necessary in establishing the scope of their examination
of the Company's consolidated financial statements as of September 30, 1999, did
not disclose any weaknesses in internal controls that they considered to be
material weaknesses.

         (h)      Officers' Certificate. You shall have received on the First
Closing Date and the Second Closing Date, as the case may be, a certificate of
the Company, dated the First Closing Date or the Second Closing Date, as the
case may be, signed by the Chief Executive Officer and Chief Financial Officer
of the Company, to the effect that, and you shall be satisfied that:

         (i)      The representations and warranties of the Company in this
         Agreement are true and correct, as if made on and as of the First
         Closing Date or the Second Closing Date, as the case may be, and the
         Company has complied with all the agreements and satisfied all the
         conditions on its part to be performed or satisfied at or prior to the
         First Closing Date or the Second Closing Date, as the case may be;

         (ii)     No stop order suspending the effectiveness of the Registration
         Statement has been issued and no proceedings for that purpose have been
         instituted or are pending or threatened under the Act;

         (iii)    When the Registration Statement became effective and at all
         times subsequent thereto up to the delivery of such certificate, the
         Registration Statement and the Prospectus, and any amendments or
         supplements thereto contained all material information required to be
         included therein by the Securities Act or the Exchange Act and the
         applicable rules and regulations of the Commission thereunder, as the
         case may be, and in all material respects conformed to the requirements
         of the Securities Act or the Exchange Act and the applicable rules and
         regulations of the Commission thereunder, as the case may be, the
         Registration Statement and the Prospectus, and any amendments or
         supplements thereto, did not and does not include any 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 not
         misleading; and, since the effective date of the Registration
         Statement, there has occurred no event required to be set forth in an
         amended or supplemented Prospectus which has not been so set forth; and

         (iv)     Subsequent to the respective dates as of which information is
         given in the Registration Statement and Prospectus, there has not been
         (a) any Material Adverse Change, (b) any transaction that is material
         to the Company and its subsidiaries considered as one enterprise,
         except transactions entered into in the ordinary course of business,
         (c) any obligation, direct or contingent, that is material to the
         Company and its subsidiaries considered as one enterprise, incurred by
         the Company or its subsidiaries, except obligations incurred in the
         ordinary course of business, (d) any change in the


                                       16.
<PAGE>   17

         capital stock or outstanding indebtedness of the Company or any of its
         subsidiaries that is material to the Company and its subsidiaries
         considered as one enterprise, (e) any dividend or distribution of any
         kind declared, paid or made on the capital stock of the Company or any
         of its subsidiaries, or (f) any loss or damage (whether or not insured)
         to the property of the Company or any of its subsidiaries which has
         been sustained or will have been sustained which has a Material Adverse
         Effect.

         (i)      Lock-up Agreement from Certain Stockholders of the Company.
The Company shall have obtained and delivered the Lock-up Agreements to you from
each officer and director of the Company.

         (j)      Nasdaq Listing. The Shares shall have been approved for
listing on the Nasdaq National Market, subject only to official notice of
issuance.

         (k)      Compliance with Prospectus Delivery Requirements. The Company
shall have complied with the provisions of Sections 2(g) and 3(e) hereof with
respect to the furnishing of Prospectuses.

         (l)      Additional Documents. On or before each of the First Closing
Date and the Second Closing Date, as the case may be, the Representatives and
counsel for the Underwriters shall have received such information, documents and
opinions as they may reasonably require for the purposes of enabling them to
pass upon the issuance and sale of the Shares as contemplated herein, or in
order to evidence the accuracy of any of the representations and warranties, or
the satisfaction of any of the conditions or agreements, herein contained.

                  If any condition specified in this Section 4 is not satisfied
when and as required to be satisfied, this Agreement may be terminated by the
Representatives by notice to the Company at any time on or prior to the First
Closing Date and, with respect to the Option Shares, at any time prior to the
Second Closing Date, which termination shall be without liability on the part of
any party to any other party, except that Section 5 (Payment of Expenses),
Section 6 (Reimbursement of Underwriters' Expenses), Section 7 (Indemnification
and Contribution) and Section 10 (Representations and Indemnities to Survive
Delivery) shall at all times be effective and shall survive such termination.

         SECTION 5.        PAYMENT OF EXPENSES. The Company agrees to pay all
costs, fees and expenses incurred in connection with the performance of its
obligations hereunder and in connection with the transactions contemplated
hereby, including without limitation (i) all expenses incident to the issuance
and delivery of the Common Stock (including all printing and engraving costs),
(ii) all fees and expenses of the registrar and transfer agent of the Common
Stock, (iii) all necessary issue, transfer and other stamp taxes in connection
with the issuance and sale of the Shares to the Underwriters, (iv) all fees and
expenses of the Company's counsel, independent public or certified public
accountants and other advisors, (v) all costs and expenses incurred in
connection with the preparation, printing, filing, shipping and distribution of
the Registration Statement (including financial statements, exhibits, schedules,
consents and certificates of experts), each preliminary prospectus and the
Prospectus, and all amendments and supplements thereto, and this Agreement, (vi)
all filing fees, attorneys' fees and expenses incurred by the Company or the
Underwriters in connection with qualifying or registering (or obtaining
exemptions from the qualification or registration of) all or any part of the
Shares for offer and sale under the state securities or blue sky laws or the
provincial securities laws of Canada or any other country, and, if requested by
the Representatives, preparing and printing a


                                       17.
<PAGE>   18

"Blue Sky Survey", an "International Blue Sky Survey" or other memorandum, and
any supplements thereto, advising the Underwriters of such qualifications,
registrations and exemptions, (vii) the filing fees incident to, and the
reasonable fees and expenses of counsel for the Underwriters in connection with,
the National Association of Securities Dealers, LLC review and approval of the
Underwriters' participation in the offering and distribution of the Common
Shares, (viii) the fees and expenses associated with listing the Common Shares
on the Nasdaq National Market, (ix) all costs and expenses incident to the
travel and accommodation of the Company's employees on the "roadshow", and (x)
all other fees, costs and expenses referred to in Item 14 of Part II of the
Registration Statement. Except as provided in this Section 5, Section 6, and
Section 7 hereof, the Underwriters shall pay their own expenses, including the
fees and disbursements of their counsel.

         SECTION 6.        REIMBURSEMENT OF UNDERWRITERS' EXPENSES. If this
Agreement is terminated by the Representatives pursuant to Section 4, Section 8,
or Section 9 or if the sale to the Underwriters of the Shares on the First
Closing Date is not consummated because of any refusal, inability or failure on
the part of the Company to perform any agreement herein or to comply with any
provision hereof, the Company agrees to reimburse the Representatives and the
other Underwriters (or such Underwriters as have terminated this Agreement with
respect to themselves), severally, upon demand for all out-of-pocket expenses
that shall have been reasonably incurred by the Representatives and the
Underwriters in connection with the proposed purchase and the offering and sale
of the Shares, including but not limited to fees and disbursements of counsel,
printing expenses, travel and accommodation expenses, postage, facsimile and
telephone charges.

         SECTION 7.        INDEMNIFICATION AND CONTRIBUTION.

         (a)      Indemnification of the Underwriters.

         Company agrees to indemnify and hold harmless each Underwriter, its
officers and employees, and each person, if any, who controls any Underwriter
within the meaning of the Securities Act and the Exchange Act against any loss,
claim, damage, liability or expense, as incurred, to which such Underwriter or
such controlling person may become subject, under the Securities Act, the
Exchange Act or other federal or state statutory law or regulation, or at common
law or otherwise (including in settlement of any litigation, if such settlement
is effected with the written consent of the Company, which consent shall not be
unreasonably withheld), insofar as such loss, claim, damage, liability or
expense (or actions in respect thereof as contemplated below) arises out of or
is based (i) upon any untrue statement or alleged untrue statement of a material
fact contained in the Registration Statement, or any amendment thereto,
including any information deemed to be a part thereof pursuant to Rule 430A or
434 under the Securities Act, or the omission or alleged omission therefrom of a
material fact required to be stated therein or necessary to make the statements
therein not misleading; or (ii) upon any untrue statement or alleged untrue
statement of a material fact contained in any preliminary prospectus or the
Prospectus (or any amendment or supplement thereto), or the omission or alleged
omission therefrom of a material fact necessary in order to make the statements
therein, in the light of the circumstances under which they were made, not
misleading; or (iii) in whole or in part upon any inaccuracy in the
representations and warranties of the Company contained herein; or (iv) in whole
or in part upon any failure of the Company to perform its obligations hereunder
or under law; or (v) any untrue statement or alleged untrue statement of any
material fact contained in any audio or visual materials provided by the Company
or based upon written information furnished by or on behalf of the Company
including, without limitation, slides, videos, films or tape recordings, used in
connection with the marketing of the Shares or (vi) any


                                      18.
<PAGE>   19

act or failure to act or any alleged act or failure to act by any Underwriter in
connection with, or relating in any manner to, the Shares or the offering
contemplated hereby, and which is included as part of or referred to in any
loss, claim, damage, liability or action arising out of or based upon any matter
covered by clause (i), (ii), (iii), (iv) or (v) above, provided that the Company
shall not be liable under this clause (vi) to the extent that a court of
competent jurisdiction shall have determined by a final judgment that such loss,
claim, damage, liability or action resulted directly from any such acts or
failures to act undertaken or omitted to be taken by such Underwriter through
its bad faith or willful misconduct; and to reimburse each Underwriter and each
such controlling person for any and all expenses (including the fees and
disbursements of counsel chosen by Robertson Stephens) as such expenses are
reasonably incurred by such Underwriter or such controlling person in connection
with investigating, defending, settling, compromising or paying any such loss,
claim, damage, liability, expense or action; provided, however, that the
foregoing indemnity agreement shall not apply to any loss, claim, damage,
liability or expense to the extent, but only to the extent, arising out of or
based upon any untrue statement or alleged untrue statement or omission or
alleged omission made in reliance upon and in conformity with written
information furnished to the Company by the Representatives expressly for use in
the Registration Statement, any preliminary prospectus or the Prospectus (or any
amendment or supplement thereto). The indemnity agreement set forth in this
Section 7(a) shall be in addition to any liabilities that the Company may
otherwise have.

         (b)      Indemnification of the Company, its Directors and Officers.
Each Underwriter agrees, severally and not jointly, to indemnify and hold
harmless the Company, each of its directors, each of its officers who signed the
Registration Statement and each person, if any, who controls the Company within
the meaning of the Securities Act or the Exchange Act, against any loss, claim,
damage, liability or expense, as incurred, to which the Company, or any such
director, officer or controlling person may become subject, under the Securities
Act, the Exchange Act, or other federal or state statutory law or regulation, or
at common law or otherwise (including in settlement of any litigation, if such
settlement is effected with the written consent of such Underwriter), insofar as
such loss, claim, damage, liability or expense (or actions in respect thereof as
contemplated below) arises out of or is based upon any untrue or alleged untrue
statement of a material fact contained in the Registration Statement, any
preliminary prospectus or the Prospectus (or any amendment or supplement
thereto), or arises out of or is based upon the omission or alleged omission to
state therein a material fact required to be stated therein 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 the Registration Statement, any preliminary
prospectus, the Prospectus (or any amendment or supplement thereto), in reliance
upon and in conformity with written information furnished to the Company by the
Representatives expressly for use therein; and to reimburse the Company, or any
such director, officer or controlling person for any legal and other expense
reasonably incurred by the Company, or any such director, officer or controlling
person in connection with investigating, defending, settling, compromising or
paying any such loss, claim, damage, liability, expense or action. The indemnity
agreement set forth in this Section 7(b) shall be in addition to any liabilities
that each Underwriter may otherwise have.

         (c)      Information Provided by the Underwriters. The Company and each
person, if any, who controls the Company within the meaning of the Securities
Act or the Exchange Act, hereby acknowledges that the only information that the
Underwriters have furnished to the Company expressly for use in the Registration
Statement, any preliminary prospectus or the Prospectus (or any amendment or
supplement thereto) are the statements set forth in the table


                                      19.
<PAGE>   20

in the first paragraph and the second paragraph under the caption "Underwriting"
in the Prospectus; and the Underwriters confirm that such statements are
correct.

         (d)      Notifications and Other Indemnification Procedures. Promptly
after receipt by an indemnified party under this Section 7 of notice of the
commencement of any action, such indemnified party will, if a claim in respect
thereof is to be made against an indemnifying party under this Section 7, notify
the indemnifying party in writing of the commencement thereof, but the omission
so to notify the indemnifying party will not relieve it from any liability which
it may have to any indemnified party for contribution or otherwise under the
indemnity agreement contained in this Section 7 or to the extent it is not
prejudiced as a proximate result of such failure. In case any such action is
brought against any indemnified party and such indemnified party seeks or
intends to seek indemnity from an indemnifying party, the indemnifying party
will be entitled to participate in, and, to the extent that it shall elect,
jointly with all other indemnifying parties similarly notified, by written
notice delivered to the indemnified party promptly after receiving the aforesaid
notice from such indemnified party, to assume the defense thereof with counsel
reasonably satisfactory to such indemnified party; provided, however, if the
defendants in any such action include both the indemnified party and the
indemnifying party and the indemnified party shall have reasonably concluded
that a conflict may arise between the positions of the indemnifying party and
the indemnified party in conducting the defense of any such action or that there
may be legal defenses available to it and/or other indemnified parties which are
different from or additional to those available to the indemnifying party, the
indemnified party or parties shall have the right to select separate counsel to
assume such legal defenses and to otherwise participate in the defense of such
action on behalf of such indemnified party or parties. Upon receipt of notice
from the indemnifying party to such indemnified party of such indemnifying
party's election so to assume the defense of such action and approval by the
indemnified party of counsel, the indemnifying party will not be liable to such
indemnified party under this Section 7 for any legal or other expenses
subsequently incurred by such indemnified party in connection with the defense
thereof unless (i) the indemnified party shall have employed separate counsel in
accordance with the proviso to the next preceding sentence (it being understood,
however, that the indemnifying party shall not be liable for the expenses of
more than one separate counsel (together with local counsel), approved by the
indemnifying party (Robertson Stephens in the case of Section 7(b) and Section
8), representing the indemnified parties who are parties to such action), (ii)
the indemnifying party shall not have employed counsel satisfactory to the
indemnified party to represent the indemnified party within a reasonable time
after notice of commencement of the action, or (iii) the indemnifying party has
authorized the employment of counsel for the indemnified party at the expense of
the indemnifying party, in each of which cases the fees and expenses of counsel
shall be at the expense of the indemnifying party.

         (e)      Settlements. The indemnifying party under this Section 7 shall
not be liable for any settlement of any proceeding effected without its written
consent, which consent shall not be unreasonably withheld, but if settled with
such consent or if there be a final judgment for the plaintiff, the indemnifying
party agrees to indemnify the indemnified party against any loss, claim, damage,
liability or expense by reason of such settlement or judgment. Notwithstanding
the foregoing sentence, if at any time an indemnified party shall have requested
an indemnifying party to reimburse the indemnified party for fees and expenses
of counsel as contemplated by Section 7(d) hereof, the indemnifying party agrees
that it shall be liable for any settlement of any proceeding effected without
its written consent if (i) such settlement is entered into more than 60 days
after receipt by such indemnifying party of the aforesaid request and (ii) such
indemnifying party shall not have reimbursed the indemnified party in accordance
with such request prior to the date of such settlement. No indemnifying party
shall, without the prior


                                      20.
<PAGE>   21

written consent of the indemnified party, effect any settlement, compromise or
consent to the entry of judgment in any pending or threatened action, suit or
proceeding in respect of which any indemnified party is or could have been a
party and indemnity was or could have been sought hereunder by such indemnified
party, unless such settlement, compromise or consent includes (i) an
unconditional release of such indemnified party from all liability on claims
that are the subject matter of such action, suit or proceeding 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.

         (f)      Contribution. If the indemnification provided for in this
Section 7 is unavailable to or insufficient to hold harmless an indemnified
party under Section 7(a) or (b) above in respect of any losses, claims, damages
or liabilities (or actions or proceedings in respect thereof) then each
indemnifying party shall contribute to the aggregate amount paid or payable by
such indemnified party in such proportion as is appropriate to reflect the
relative benefits received by such party on the one hand and the Underwriters on
the other from the offering of the Shares. If, however, the allocation provided
by the immediately preceding sentence is not permitted by applicable law 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 such party on the one hand
and the Underwriters on the other in connection with the statements or omissions
which resulted in such losses, claims, damages or liabilities, (or actions or
proceedings in respect thereof), as well as any other relevant equitable
considerations. 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 Underwriters 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 Underwriters agree that it would not be just
and equitable if contributions pursuant to this Section 7(f) were determined by
pro rata allocation (even if the Underwriters 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 Section 7(f). The
amount paid or payable by an indemnified party as a result of the losses,
claims, damages or liabilities (or actions or proceedings in respect thereof)
referred to above in this Section 7(f) 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 (f), (i) no Underwriter shall be required to
contribute any amount in excess of the underwriting discounts and commissions
applicable to the Shares purchased by such Underwriter and (ii) 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 Underwriters' obligations in
this Section 7(f) to contribute are several in proportion to their respective
underwriting obligations and not joint.

         (g)      Timing of Any Payments of Indemnification. Any losses, claims,
damages, liabilities or expenses for which an indemnified party is entitled to
indemnification or contribution under this Section 7 shall be paid by the
indemnifying party to the indemnified party as such losses, claims, damages,
liabilities or expenses are incurred, but in all cases, no later than forty-five
(45) days of invoice to the indemnifying party.

         (h)      Survival. The indemnity and contribution agreements contained
in this Section 7 and the representation and warranties set forth in this
Agreement shall remain operative and in full force and effect, regardless of (i)
any investigation made by or on behalf of any Underwriter


                                      21.
<PAGE>   22

or any person controlling any Underwriter, the Company, its directors or
officers or any persons controlling the Company, (ii) acceptance of any Shares
and payment therefor hereunder, and (iii) any termination of this Agreement. A
successor to any Underwriter, or to the Company, its directors or officers, or
any person controlling the Company, shall be entitled to the benefits of the
indemnity, contribution and reimbursement agreements contained in this Section
7.

         (i)      Acknowledgements of Parties. The parties to this Agreement
hereby acknowledge that they are sophisticated business persons who were
represented by counsel during the negotiations regarding the provisions hereof
including, without limitation, the provisions of this Section 7, and are fully
informed regarding said provisions. They further acknowledge that the provisions
of this Section 7 fairly allocate the risks in light of the ability of the
parties to investigate the Company and its business in order to assure that
adequate disclosure is made in the Registration Statement and Prospectus as
required by the Securities Act and the Exchange Act.

         SECTION 8.        DEFAULT OF ONE OR MORE OF THE SEVERAL UNDERWRITERS.
If, on the First Closing Date or the Second Closing Date, as the case may be,
any one or more of the several Underwriters shall fail or refuse to purchase
Shares that it or they have agreed to purchase hereunder on such date, and the
aggregate number of Common Shares which such defaulting Underwriter or
Underwriters agreed but failed or refused to purchase does not exceed 10% of the
aggregate number of the Shares to be purchased on such date, the other
Underwriters shall be obligated, severally, in the proportions that the number
of Firm Common Shares set forth opposite their respective names on Schedule A
bears to the aggregate number of Firm Shares set forth opposite the names of all
such non-defaulting Underwriters, or in such other proportions as may be
specified by the Representatives with the consent of the non-defaulting
Underwriters, to purchase the Shares which such defaulting Underwriter or
Underwriters agreed but failed or refused to purchase on such date. If, on the
First Closing Date or the Second Closing Date, as the case may be, any one or
more of the Underwriters shall fail or refuse to purchase Shares and the
aggregate number of Shares with respect to which such default occurs exceeds 10%
of the aggregate number of Shares to be purchased on such date, and arrangements
satisfactory to the Representatives and the Company for the purchase of such
Shares are not made within 48 hours after such default, this Agreement shall
terminate without liability of any party to any other party except that the
provisions of Section 5, Section 6 and Section 7 shall at all times be effective
and shall survive such termination. In any such case either the Representatives
or the Company shall have the right to postpone the First Closing Date or the
Second Closing Date, as the case may be, but in no event for longer than seven
days in order that the required changes, if any, to the Registration Statement
and the Prospectus or any other documents or arrangements may be effected.

                  As used in this Agreement, the term "Underwriter" shall be
deemed to include any person substituted for a defaulting Underwriter under this
Section 8. Any action taken under this Section 8 shall not relieve any
defaulting Underwriter from liability in respect of any default of such
Underwriter under this Agreement.

         SECTION 9.        TERMINATION OF THIS AGREEMENT. This Agreement may be
terminated by the Representatives by notice given to the Company if (a) at any
time after the execution and delivery of this Agreement and prior to the First
Closing Date (i) trading or quotation in any of the Company's securities shall
have been suspended or limited by the Commission or by the Nasdaq Stock Market,
or trading in securities generally on either the Nasdaq Stock Market or the NASD
shall have been suspended or limited, or minimum or maximum prices shall have
been generally established on any of such stock exchanges by the Commission or
the National


                                      22.
<PAGE>   23

Association of Securities Dealers, LLC; (ii) a general banking moratorium shall
have been declared by any of federal, New York, Delaware or California
authorities; (iii) there shall have occurred any outbreak or escalation of
national or international hostilities or any crisis or calamity, or any change
in the United States or international financial markets, or any substantial
change or development involving a prospective change in United States' or
international political, financial or economic conditions, as in the judgment of
the Representatives is material and adverse and makes it impracticable or
inadvisable to market the Shares in the manner and on the terms contemplated in
the Prospectus or to enforce contracts for the sale of securities; (iv) in the
judgment of the Representatives there shall have occurred any Material Adverse
Change; or (v) the Company shall have sustained a loss by strike, fire, flood,
earthquake, accident or other calamity of such character as in the judgment of
the Representatives may interfere materially with the conduct of the business
and operations of the Company regardless of whether or not such loss shall have
been insured or (b) in the case of any of the events specified in Sections
9(a)(i)-(v), such event singly or together with any other event, makes it, in
your judgement, impracticable or inadvisable to market the Shares in the manner
and on the terms contemplated in the Prospectus. Any termination pursuant to
this Section 9 shall be without liability on the part of (x) the Company to any
Underwriter, except that the Company shall be obligated to reimburse the
expenses of the Representatives and the Underwriters pursuant to Sections 5 and
6 hereof, (y) any Underwriter to the Company or any person controlling the
Company, or (z) of any party hereto to any other party except that the
provisions of Section 7 shall at all times be effective and shall survive such
termination.

         SECTION 10.       REPRESENTATIONS AND INDEMNITIES TO SURVIVE DELIVERY.
The respective indemnities, agreements, representations, warranties and other
statements of the Company or any person controlling the company, of its
officers, and of the several Underwriters set forth in or made pursuant to this
Agreement will remain in full force and effect, regardless of any investigation
made by or on behalf of any Underwriter or the Company or any of its or their
partners, officers or directors or any controlling person, as the case may be,
and will survive delivery of and payment for the Shares sold hereunder and any
termination of this Agreement.

         SECTION 11.       NOTICES. All communications hereunder shall be in
writing and shall be mailed, hand delivered or telecopied and confirmed to the
parties hereto as follows:

If to the Representatives:

         ROBERTSON STEPHENS, INC.
         555 California Street
         San Francisco, California 94104
         Facsimile: (415) 676-2675
         Attention: General Counsel

If to the Company [or the Principal Subsidiary]:

         OSI Pharmaceuticals, Inc.
         106 Charles Linbergh Blvd.
         Uniondale, NY 11553-3644
         Facsimile: (516) 222-0114
         Attention: Colin Goddard

Any party hereto may change the address for receipt of communications by giving
written notice to the others.


                                      23.
<PAGE>   24

         SECTION 12.       SUCCESSORS. This Agreement will inure to the benefit
of and be binding upon the parties hereto, including any substitute Underwriters
pursuant to Section 8 hereof, and to the benefit of the employees, officers and
directors and controlling persons referred to in Section 7, and to their
respective successors, and no other person will have any right or obligation
hereunder. The term "successors" shall not include any purchaser of the Shares
as such from any of the Underwriters merely by reason of such purchase.

         SECTION 13.       PARTIAL UNENFORCEABILITY. The invalidity or
unenforceability of any Section, paragraph or provision of this Agreement shall
not affect the validity or enforceability of any other Section, paragraph or
provision hereof. If any Section, paragraph or provision of this Agreement is
for any reason determined to be invalid or unenforceable, there shall be deemed
to be made such minor changes (and only such minor changes) as are necessary to
make it valid and enforceable.

         SECTION 14.       GOVERNING LAW PROVISIONS.

         (a)      Governing Law. This agreement shall be governed by and
construed in accordance with the internal laws of the State of New York
applicable to agreements made and to be performed in such state.

         (b)      Consent to Jurisdiction. Any legal suit, action or proceeding
arising out of or based upon this Agreement or the transactions contemplated
hereby ("Related Proceedings") may be instituted in the federal courts of the
United States of America located in the City and County of San Francisco or the
courts of the State of California in each case located in the City and County of
San Francisco (collectively, the "Specified Courts"), and each party irrevocably
submits to the personal jurisdiction (except for proceedings instituted in
regard to the enforcement of a judgment of any such court (a "Related
Judgment"), as to which such jurisdiction is non-exclusive) of such courts in
any such suit, action or proceeding. Service of any process, summons, notice or
document by mail to such party's address set forth above shall be effective
service of process for any suit, action or other proceeding brought in any such
court. The parties irrevocably and unconditionally waive any objection to the
laying of venue of any suit, action or other proceeding in the Specified Courts
and irrevocably and unconditionally waive and agree not to plead or claim in any
such court that any such suit, action or other proceeding brought in any such
court has been brought in an inconvenient forum. Each party not located in the
United States irrevocably appoints CT Corporation System, which currently
maintains a San Francisco office at 49 Stevenson Street, San Francisco,
California 94105, United States of America, as its agent to receive service of
process or other legal summons for purposes of any such suit, action or
proceeding that may be instituted in any state or federal court in the City and
County of San Francisco.

         SECTION 15.       GENERAL PROVISIONS. This Agreement constitutes the
entire agreement of the parties to this Agreement and supersedes all prior
written or oral and all contemporaneous oral agreements, understandings and
negotiations with respect to the subject matter hereof. This Agreement may be
executed in two or more counterparts, each one of which shall be an original,
with the same effect as if the signatures thereto and hereto were upon the same
instrument. This Agreement may not be amended or modified unless in writing by
all of the parties hereto, and no condition herein (express or implied) may be
waived unless waived in writing by each party whom the condition is meant to
benefit. Section headings herein are for the convenience of the parties only and
shall not affect the construction or interpretation of this Agreement.


                                      24.
<PAGE>   25

         [The remainder of this page has been intentionally left blank.]


                                      25.
<PAGE>   26

                  If the foregoing is in accordance with your understanding of
our agreement, please sign and return to the Company the enclosed copies hereof,
whereupon this instrument, along with all counterparts hereof, shall become a
binding agreement in accordance with its terms.

                                    Very truly yours,

                                             OSI PHARMACEUTICALS, INC.,
                                             A DELAWARE CORPORATION


                                    By:
                                       -----------------------------------------
                                       Name:
                                       -----------------------------------------
                                       Title:
                                       -----------------------------------------

                  The foregoing Underwriting Agreement is hereby confirmed and
accepted by the Representatives as of the date first above written.

ROBERTSON STEPHENS, INC.
LEHMAN BROTHERS INC.
PRUDENTIAL SECURITIES INCORPORATED
LAZARD FRERES & CO. LLC
ADAMS, HARKNESS & HILL, INC.

On their behalf and on behalf of each of the several underwriters named in
Schedule A hereto.

BY ROBERTSON STEPHENS, INC.


By:
   --------------------------------------------
    Mitch Whiteford


                                      26.
<PAGE>   27

                                   SCHEDULE A

<TABLE>
<CAPTION>
                                                         NUMBER OF FIRM COMMON
                 UNDERWRITERS                           SHARES TO BE PURCHASED
                 ------------                           ----------------------
<S>                                                     <C>
ROBERTSON STEPHENS, INC. ................................       [___]

LEHMAN BROTHERS, INC. ...................................       [___]

PRUDENTIAL SECURITIES INCORPORATED ......................       [___]

LAZARD FRERES & CO. LLC .................................       [___]

ADAMS, HARKNESS & HILL, INC. ............................       [___]

         Total ..........................................       [___]
</TABLE>


                                       S-A


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