EXHIBIT 1.1

                                 Maxygen, Inc.

                                 Common Stock
                          par value $0.0001 per share


                                --------------

                            Underwriting Agreement
                            ----------------------

                                                                November__, 1999

Goldman, Sachs & Co.,
BancBoston Robertson Stephens, Inc.
Invemed Associates LLC
 As representatives of the several Underwriters
  named in Schedule I hereto,
c/o Goldman, Sachs & Co.
85 Broad Street,
New York, New York 10004.

Ladies and Gentlemen:

     Maxygen, Inc., a Delaware corporation (the "Company"), proposes, subject to
the terms and conditions stated herein, to issue and sell to the Underwriters
named in Schedule I hereto (the "Underwriters") an aggregate of ........ shares
(the "Firm Shares") and, at the election of the Underwriters, up to ........
additional shares (the "Optional Shares") of Common Stock, par value $.0001
("Stock") of the Company (the Firm Shares and the Optional Shares that the
Underwriters elect to purchase pursuant to Section 2 hereof being collectively
called the "Shares").

     1.  The Company represents and warrants to, and agrees with, each of the
Underwriters that:

     (a) A registration statement on Form S-1 (File No. 333-89413) (the "Initial
Registration Statement") in respect of the Shares has been filed with the
Securities and Exchange Commission (the "Commission"); the Initial Registration
Statement and any post-effective amendment thereto, each in the form heretofore
delivered to you, and, excluding exhibits thereto, to you for each of the other
Underwriters, have been declared effective by the Commission in such form; other
than a registration statement, if any, increasing the size of the offering (a
"Rule 462(b) Registration Statement"), filed pursuant to Rule 462(b) under the
Securities Act of 1933, as amended (the "Act"), which became effective upon
filing, no other document with respect to the Initial Registration Statement has
heretofore been filed with the Commission; and no stop order suspending the
effectiveness of the Initial Registration Statement, any post-effective
amendment thereto or the Rule 462(b) Registration Statement, if any, has been
issued and no proceeding for that purpose has been initiated or threatened by
the Commission (any preliminary prospectus included in the Initial Registration
Statement or filed with the Commission pursuant to Rule 424(a) of the rules and


regulations of the Commission under the Act is hereinafter called a "Preliminary
Prospectus"; the various parts of the Initial Registration Statement and the
Rule 462(b) Registration Statement, if any, including all exhibits thereto and
including the information contained in the form of final prospectus filed with
the Commission pursuant to Rule 424(b) under the Act in accordance with Section
5(a) hereof and deemed by virtue of Rule 430A under the Act to be part of the
Initial Registration Statement at the time it was declared effective, each as
amended at the time such part of the Initial Registration Statement became
effective or such part of the Rule 462(b) Registration Statement, if any, became
or hereafter becomes effective, are hereinafter collectively called the
"Registration Statement"; such final prospectus, in the form first filed
pursuant to Rule 424(b) under the Act, is hereinafter called the "Prospectus";

     (b) No order preventing or suspending the use of any Preliminary Prospectus
has been issued by the Commission, and each Preliminary Prospectus, at the time
of filing thereof, conformed in all material respects to the requirements of the
Act and the rules and regulations of the Commission thereunder, and did not
contain an untrue statement of a material fact or omit to state a material fact
required to be stated therein or necessary to make the statements therein, in
the light of the circumstances under which they were made, not misleading;
provided, however, that this representation and warranty shall not apply to any
statements or omissions made in reliance upon and in conformity with information
furnished in writing to the Company by an Underwriter through Goldman, Sachs &
Co. expressly for use therein;

     (c) The Registration Statement conforms, and the Prospectus and any further
amendments or supplements to the Registration Statement or the Prospectus will
conform, in all material respects to the requirements of the Act and the rules
and regulations of the Commission thereunder and do not and will not, as of the
applicable effective date as to the Registration Statement and any amendment
thereto, and as of the applicable filing date as to the Prospectus and any
amendment or supplement thereto, contain an untrue statement of a material fact
or omit to state a material fact required to be stated therein or necessary to
make the statements therein not misleading; provided, however, that this
representation and warranty shall not apply to any statements or omissions made
in reliance upon and in conformity with information furnished in writing to the
Company by an Underwriter through Goldman, Sachs & Co. expressly for use
therein;

     (d) Neither the Company nor any of its subsidiaries has sustained since the
date of the latest audited financial statements included in the Prospectus any
material loss or interference with its business from fire, explosion, flood or
other calamity, whether or not covered by insurance, or from any labor dispute
or court or governmental action, order or decree, otherwise than as set forth or
contemplated in the Prospectus; and, since the respective dates as of which
information is given in the Registration Statement and the Prospectus, there has
not been any change in the capital stock (other than upon the exercise of
options granted pursuant to employee or director stock option plans)  or long-
term debt of the Company or any of its subsidiaries or any material adverse
change, or any development involving a prospective material adverse change, in
or affecting the general affairs, management, financial position, stockholders'
equity or results of operations of the Company and its subsidiaries, otherwise
than as set forth or contemplated in the Prospectus;

     (e) The Company and its subsidiaries have good and marketable title in fee
simple to all real property and good and marketable title to all personal
property owned by them, in each case free and clear of all liens, encumbrances
and defects except such as are described in the Prospectus or such as do not
materially affect the value of such property and do not materially interfere
with the use

                                      F-2


made and proposed to be made of such property by the Company and its
subsidiaries; and any real property and buildings held under lease by the
Company and its subsidiaries are held by them under valid, subsisting and
enforceable leases with such exceptions as are not material and do not
interfere with the use made and proposed to be made of such property and
buildings by the Company and its subsidiaries;

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

     (g) The Company has an authorized capitalization as set forth in the
Prospectus, and all of the issued shares of capital stock of the Company have
been duly and validly authorized and issued, are fully paid and non-assessable
and conform to the description of the Stock contained in the Prospectus; and all
of the issued shares of capital stock of each subsidiary of the Company have
been duly and validly authorized and issued, are fully paid and non-assessable
and (except for directors' qualifying shares) are owned directly or indirectly
by the Company, free and clear of all liens, encumbrances, equities or claims;

     (h) The unissued Shares to be issued and sold by the Company to the
Underwriters hereunder have been duly and validly authorized and, when issued
and delivered against payment therefor as provided herein, will be duly and
validly issued and fully paid and non-assessable and will conform to the
description of the Stock contained in the Prospectus;

     (i) The issue and sale of the Shares by the Company and the compliance by
the Company with all of the provisions of this Agreement and the consummation of
the transactions herein contemplated will not conflict with or result in a
breach or violation of any of the terms or provisions of, or constitute a
default under, any indenture, mortgage, deed of trust, loan agreement or other
material agreement or material instrument to which the Company or any of its
subsidiaries is a party or by which the Company or any of its subsidiaries is
bound or to which any of the property or assets of the Company or any of its
subsidiaries is subject, nor will such action result in any violation of the
provisions of the Certificate of Incorporation or By-laws of the Company or any
statute or any order, rule or regulation of any court or governmental agency or
body having jurisdiction over the Company or any of its subsidiaries or any of
their properties; and no consent, approval, authorization, order, registration
or qualification of or with any such court or governmental agency or body is
required for the issue and sale of the Shares or the consummation by the Company
of the transactions contemplated by this Agreement, except the registration
under the Act of the Shares and such consents, approvals, authorizations,
registrations or qualifications as may be required under state securities or
Blue Sky laws in connection with the purchase and distribution of the Shares by
the Underwriters;

     (j) Neither the Company nor any of its subsidiaries is in violation of its
Certificate of Incorporation or By-laws or in default in the performance or
observance of any material obligation, agreement, covenant or condition
contained in any indenture, mortgage, deed of trust, loan

                                      F-3


agreement, lease or other agreement or instrument to which it is a party or by
which it or any of its properties may be bound;

     (k) The statements set forth in the Prospectus under the caption
"Description of Capital Stock", insofar as they purport to constitute a summary
of the terms of the Stock and under the caption "Underwriting", insofar as they
purport to describe the provisions of the laws and documents referred to
therein, are accurate, complete and fair;

     (l) Other than as set forth in the Prospectus, there are no legal or
governmental proceedings pending to which the Company or any of its subsidiaries
is a party or of which any property of the Company or any of its subsidiaries is
the subject which, if determined adversely to the Company or any of its
subsidiaries, would individually or in the aggregate have a material adverse
effect on the current or future consolidated financial position, stockholders'
equity or results of operations of the Company and its subsidiaries; and, to the
best of the Company's knowledge, no such proceedings are threatened or
contemplated by governmental authorities or threatened by others;

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

     (n) Neither the Company nor any of its affiliates does business with the
government of Cuba or with any person or affiliate located in Cuba within the
meaning of Section 517.075, Florida Statutes;

     (o) Ernst & Young, LLP, who have certified certain financial statements of
the Company and its subsidiaries, are independent public accountants as required
by the Act and the rules and regulations of the Commission thereunder; and

     (p) Except for the Shares, the holders of all outstanding shares of Stock,
and all securities convertible into or exercisable or exchangeable for Stock,
have delivered agreements (collectively, the "Lock-up Agreements") that restrict
the holders thereof from, among other things, selling, granting any option for
the purchase of, pledging, or otherwise transferring or disposing of the
economic interest in, any of such shares of Stock, or any such securities
convertible into or exercisable or exchangeable for Stock, for a period of 180
days after the date of the Prospectus without the prior written consent of
Goldman, Sachs & Co.; and the Company has no reason to believe any Lock-up
Agreement is not a valid and binding obligation of each party thereto other than
the Underwriters; and

     (q) The Company has imposed a stop-transfer instruction with the Company's
transfer agent in order to enforce the Lock-up Agreements.

     (r) The Company (i) to the extent the Company is required under any of its
equity incentive plans or any agreement affecting its capital stock
(collectively, the "Plans"), has notified each holder of any outstanding shares
of Stock and each holder of any securities convertible into or exercisable or
exchangeable for Stock issued under the Plans that pursuant to the terms of the
Plans, none of such options or shares may be sold or otherwise transferred or
disposed of for a period of 180 days after the date of the Prospectus and (ii)
has imposed a stop-transfer instruction with the Company's transfer agent in
order to enforce the foregoing lock-up provision imposed pursuant to the Plans;

                                      F-4


     (s) The Company has reviewed its operations and that of its subsidiaries
and any third parties with which the Company or any of its subsidiaries has a
material relationship to evaluate the extent to which the business or operations
of the Company or any of its subsidiaries will be affected by the Year 2000
Problem.  As a result of such review, the Company has no reason to believe, and
does not believe, that the Year 2000 Problem will have a material adverse effect
on the general affairs, management, the current or future consolidated financial
position, business prospects, stockholders' equity or results of operations of
the Company and its subsidiaries or result in any material loss or interference
with the Company's business or operations.  The "Year 2000 Problem" as used
herein means any significant risk that computer hardware or software used in the
receipt, transmission, processing, manipulation, storage, retrieval,
retransmission or other utilization of data or in the operation of mechanical or
electrical systems of any kind will not, in the case of dates or time periods
occurring after December 31, 1999, function at least as effectively as in the
case of dates or time periods occurring prior to January 1, 2000.

     2.  Subject to the terms and conditions herein set forth, (a) the Company
agrees to issue and sell to each of the Underwriters, and each of the
Underwriters agrees, severally and not jointly, to purchase from the Company, at
a purchase price per share of $................, the number of Firm Shares set
forth opposite the name of such Underwriter in Schedule I hereto and (b) in the
event and to the extent that the Underwriters shall exercise the election to
purchase Optional Shares as provided below, the Company agrees to issue and sell
to each of the Underwriters, and each of the Underwriters agrees, severally and
not jointly, to purchase from the Company, at the purchase price per share set
forth in clause (a) of this Section 2, that portion of the number of Optional
Shares as to which such election shall have been exercised (to be adjusted by
you so as to eliminate fractional shares) determined by multiplying such number
of Optional Shares by a fraction, the numerator of which is the maximum number
of Optional Shares which such Underwriter is entitled to purchase as set forth
opposite the name of such Underwriter in Schedule I hereto and the denominator
of which is the maximum number of Optional Shares that all of the Underwriters
are entitled to purchase hereunder.

     The Company hereby grants to the Underwriters the right to purchase at
their election up to ................... Optional Shares, at the purchase price
per share set forth in the paragraph above, for the sole purpose of covering
sales of shares in excess of the number of Firm Shares.  Any such election to
purchase Optional Shares may be exercised only by written notice from you to the
Company, given within a period of 30 calendar days after the date of this
Agreement, setting forth the aggregate number of Optional Shares to be purchased
and the date on which such Optional Shares are to be delivered, as determined by
you but in no event earlier than the First Time of Delivery (as defined in
Section 4 hereof) or, unless you and the Company otherwise agree in writing,
earlier than two or later than ten business days after the date of such notice.

     3.  Upon the authorization by you of the release of the Firm Shares, the
several Underwriters propose to offer the Firm Shares for sale upon the terms
and conditions set forth in the Prospectus.

     4.  (a) The Shares to be purchased by each Underwriter hereunder, in
definitive form, and in such authorized denominations and registered in such
names as Goldman, Sachs & Co. may request upon at least forty-eight hours' prior
notice to the Company shall be delivered by or on behalf of the Company to
Goldman, Sachs & Co., through the facilities of the Depository Trust Company
("DTC"), for the account of such Underwriter, against payment by or on behalf of
such Underwriter of

                                      F-5


the purchase price therefor by wire transfer of Federal (same-day) funds to the
account specified by the Company to Goldman, Sachs & Co. at least forty-eight
hours in advance. The Company will cause the certificates representing the
Shares to be made available for checking and packaging at least twenty-four
hours prior to the Time of Delivery (as defined below) with respect thereto at
the office of DTC or its designated custodian (the "Designated Office"). The
time and date of such delivery and payment shall be, with respect to the Firm
Shares, 9:30 a.m., New York City time, on ............., 1999 or such other time
and date as Goldman, Sachs & Co. and the Company may agree upon in writing, and,
with respect to the Optional Shares, 9:30 a.m., New York time, on the date
specified by Goldman, Sachs & Co. in the written notice given by Goldman, Sachs
& Co. of the Underwriters' election to purchase such Optional Shares, or such
other time and date as Goldman, Sachs & Co. and the Company may agree upon in
writing. Such time and date for delivery of the Firm Shares is herein called the
"First Time of Delivery", such time and date for delivery of the Optional
Shares, if not the First Time of Delivery, is herein called the "Second Time of
Delivery", and each such time and date for delivery is herein called a "Time of
Delivery".

     (b) The documents to be delivered at each Time of Delivery by or on behalf
of the parties hereto pursuant to Section 7 hereof, including the cross receipt
for the Shares and any additional documents requested by the Underwriters
pursuant to Section 7(j) hereof, will be delivered at the offices of Heller
Ehrman White & McAuliffe, 2500 Sand Hill Road, Menlo Park, California, 94025-
7063 (the "Closing Location"), and the Shares will be delivered at the
Designated Office, all at such Time of Delivery.  A meeting will be held at the
Closing Location at 1:00 p.m., New York City time, on the New York Business Day
next preceding such Time of Delivery, at which meeting the final drafts of the
documents to be delivered pursuant to the preceding sentence will be available
for review by the parties hereto.  For the purposes of this Section 4, "New York
Business Day" shall mean each Monday, Tuesday, Wednesday, Thursday and Friday
which is not a day on which banking institutions in New York are generally
authorized or obligated by law or executive order to close.

     5.  The Company agrees with each of the Underwriters:

     (a) To prepare the Prospectus in a form approved by you and to file such
Prospectus pursuant to Rule 424(b) under the Act not later than the Commission's
close of business on the second business day following the execution and
delivery of this Agreement, or, if applicable, such earlier time as may be
required by Rule 430A(a)(3) under the Act; to make no further amendment or any
supplement to the Registration Statement or Prospectus which shall be
disapproved by you promptly after reasonable notice thereof; to advise you,
promptly after it receives notice thereof, of the time when any amendment to the
Registration Statement has been filed or becomes effective or any supplement to
the Prospectus or any amended Prospectus has been filed and to furnish you with
copies thereof; to advise you, promptly after it receives notice thereof, of the
issuance by the Commission of any stop order or of any order preventing or
suspending the use of any Preliminary Prospectus or prospectus, of the
suspension of the qualification of the Shares for offering or sale in any
jurisdiction, of the initiation or threatening of any proceeding for any such
purpose, or of any request by the Commission for the amending or supplementing
of the Registration Statement or Prospectus or for additional information; and,
in the event of the issuance of any stop order or of any order preventing or
suspending the use of any Preliminary Prospectus or prospectus or suspending any
such qualification, promptly to use its best efforts to obtain the withdrawal of
such order;

     (b) Promptly from time to time to take such action as you may reasonably
request to qualify the Shares for offering and sale under the securities laws of
such jurisdictions as you may request

                                      F-6


and to comply with such laws so as to permit the continuance of sales and
dealings therein in such jurisdictions for as long as may be necessary to
complete the distribution of the Shares, provided that in connection therewith
the Company shall not be required to qualify as a foreign corporation or to file
a general consent to service of process in any jurisdiction;

     (c) Prior to 10:00 A.M., New York City time, on the New York Business Day
next succeeding the date of this Agreement and from time to time, to furnish the
Underwriters with copies of the Prospectus in New York City in such quantities
as you may reasonably request, and, if the delivery of a prospectus is required
at any time prior to the expiration of nine months after the time of issue of
the Prospectus in connection with the offering or sale of the Shares and if at
such time any event shall have occurred as a result of which the Prospectus as
then amended or supplemented would include an untrue statement of a material
fact or omit to state any material fact necessary in order to make the
statements therein, in the light of the circumstances under which they were made
when such Prospectus is delivered, not misleading, or, if for any other reason
it shall be necessary during such period to amend or supplement the Prospectus
in order to comply with the Act, to notify you and upon your request to prepare
and furnish without charge to each Underwriter and to any dealer in securities
as many copies as you may from time to time reasonably request of an amended
Prospectus or a supplement to the Prospectus which will correct such statement
or omission or effect such compliance, and in case any Underwriter is required
to deliver a prospectus in connection with sales of any of the Shares at any
time nine months or more after the time of issue of the Prospectus, upon your
request but at the expense of such Underwriter, to prepare and deliver to such
Underwriter as many copies as you may request of an amended or supplemented
Prospectus complying with Section 10(a)(3) of the Act;

     (d) To make generally available to its securityholders as soon as
practicable, but in any event not later than eighteen months after the effective
date of the Registration Statement (as defined in Rule 158(c) under the Act), an
earnings statement of the Company and its subsidiaries (which need not be
audited) complying with Section 11(a) of the Act and the rules and regulations
thereunder (including, at the option of the Company, Rule 158);

     (e) During the period beginning from the date hereof and continuing to and
including the date 180 days after the date of the Prospectus, not to offer,
sell, contract to sell or otherwise dispose of, except as provided hereunder any
securities of the Company that are substantially similar to the Shares,
including but not limited to any securities that are convertible into or
exchangeable for, or that represent the right to receive, Stock or any such
substantially similar securities (other than pursuant to employee, director or
consultant stock option or stock purchase plans existing on, or upon the
conversion or exchange of convertible or exchangeable securities outstanding as
of, the date of this Agreement or in connection with any acquisition
transaction, provided that the recipients of the Company's securities in any
such transaction agree in writing not to offer, sell, contract to sell or
otherwise dispose of such securities during the same 180 day period), without
your prior written consent;

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

                                      F-7


     (g) During a period of five years from the effective date of the
Registration Statement, to furnish to you copies of all reports or other
communications (financial or other) furnished to stockholders, and to deliver to
you (i) as soon as they are available, copies of any reports and financial
statements furnished to or filed with the Commission or any national securities
exchange on which any class of securities of the Company is listed; and (ii)
such additional information concerning the business and financial condition of
the Company as you may from time to time reasonably request (such financial
statements to be on a consolidated basis to the extent the accounts of the
Company and its subsidiaries are consolidated in reports furnished to its
stockholders generally or to the Commission);

     (h) To use the net proceeds received by it from the sale of the Shares
pursuant to this Agreement in the manner specified in the Prospectus under the
caption "Use of Proceeds";

     (i) To use its best efforts to list for quotation the Shares on the
National Association of Securities Dealers Automated Quotations National Market
System ("NASDAQ");

     (j) To file with the Commission such information on Form 10-Q or Form 10-K
as may be required by Rule 463 under the Act;

     (k)  If the Company elects to rely upon Rule 462(b), the Company shall file
a Rule 462(b) Registration Statement with the Commission in compliance with Rule
462(b) by 10:00 P.M., Washington, D.C. time, on the date of this Agreement, and
the Company shall at the time of filing either pay to the Commission the filing
fee for the Rule 462(b) Registration Statement or give irrevocable instructions
for the payment of such fee pursuant to Rule 111(b) under the Act; and

     (l)  The Company will (i) cooperate with the Underwriters to enforce the
terms of each Lock-up Agreement (as defined in Section 1(q)), (ii) issue stop-
transfer instructions to the transfer agent for the Stock with respect to any
transaction or contemplated transaction that would constitute a breach of or
default under the applicable Lock-up Agreement, (iii) will require as a
condition to the issuance of any Stock upon exercise of options under employee
stock plans that the holders of such options execute and deliver a Lock-up
Agreement to the Company and Goldman, Sachs & Co. and (iv) upon written request
of Goldman, Sachs & Co., release from the Lock-up Agreements those shares of
Stock held by those holders set forth in such request. In addition, except with
the prior written consent of Goldman, Sachs & Co., the Company agrees not to
amend or terminate, waive any right under, or consent to any transaction that
would otherwise be prohibited under, any Lock-up Agreement, or take any other
action that would directly or indirectly have the same effect as such an
amendment, termination, waiver or consent; and

     (m)  The Company will place a restrictive legend on any shares of Stock
acquired pursuant to the exercise, after the date hereof and prior to the
expiration of the 180-day period after the date of the Prospectus, of any option
granted under the Plans (as defined in Section 1(r)), which legend shall
restrict the transfer of such shares prior to the expiration of such 180-day
period. In addition, the Company agrees that, without the prior written consent
of Goldman, Sachs & Co., it will not release any stockholder or option holder
from the market standoff provision agreed to between such stockholder or option
holder and the Company (or, if allowed, imposed by the Company) pursuant to the
terms of the Plans earlier than 180 days after the date of the Prospectus.

     6.  The Company covenants and agrees with the several Underwriters that the
Company will pay or cause to be paid the following: (i) the fees, disbursements
and expenses of the Company's counsel and accountants in connection with the
registration of the Shares under the Act and all other expenses in connection
with the preparation, printing and filing of the Registration Statement, any

                                      F-8


Preliminary Prospectus and the Prospectus and amendments and supplements thereto
and the mailing and delivering of copies thereof to the Underwriters and
dealers; (ii) the cost of printing or producing any Agreement among
Underwriters, this Agreement, the Blue Sky Memorandum, closing documents
(including any compilations thereof) and any other documents in connection with
the offering, purchase, sale and delivery of the Shares; (iii) all expenses in
connection with the qualification of the Shares for offering and sale under
state securities laws as provided in Section 5(b) hereof, including the fees and
disbursements of counsel for the Underwriters in connection with such
qualification and in connection with the Blue Sky survey (iv) all fees and
expenses in connection with listing the Shares on the NASDAQ; (v) the filing
fees incident to, and the fees and disbursements of counsel for the Underwriters
in connection with, securing any required review by the National Association of
Securities Dealers, Inc. of the terms of the sale of the Shares; (vi) the cost
of preparing stock certificates; (vii) the cost and charges of any transfer
agent or registrar; and (viii) all other costs and expenses incident to the
performance of its obligations hereunder which are not otherwise specifically
provided for in this Section.  It is understood, however, that, except as
provided in this Section, and Sections 8 and 11 hereof, the Underwriters will
pay all of their own costs and expenses, including the fees of their counsel,
stock transfer taxes on resale of any of the Shares by them, and any advertising
expenses connected with any offers they may make.

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

     (a) The Prospectus shall have been filed with the Commission pursuant to
Rule 424(b) within the applicable time period prescribed for such filing by the
rules and regulations under the Act and in accordance with Section 5(a) hereof;
if the Company has elected to rely upon Rule 462(b), the Rule 462(b)
Registration Statement shall have become effective by 10:00 P.M., Washington,
D.C. time, on the date of this Agreement; no stop order suspending the
effectiveness of the Registration Statement or any part thereof shall have been
issued and no proceeding for that purpose shall have been initiated or
threatened by the Commission; and all requests for additional information on the
part of the Commission shall have been complied with to your reasonable
satisfaction;

     (b) Wilson Sonsini Goodrich & Rosati, Professional Corporation, counsel for
the Underwriters, shall have furnished to you such written opinion or opinions
(a draft of each such opinion is attached as Annex II(a) hereto), dated such
Time of Delivery, with respect to the matters covered in paragraphs (i), (ii),
(vii), and (xiii) of subsection (c) below as well as such other related matters
as you may reasonably request, and such counsel shall have received such papers
and information as they may reasonably request to enable them to pass upon such
matters;

     (c) Heller, Ehrman White & McAuliffe, counsel for the Company, shall have
furnished to you their written opinion (a draft of such opinion is attached as
Annex II(b) hereto), dated such Time of Delivery, in form and substance
satisfactory to you, to the effect that:

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

         (ii) The Company has an authorized capitalization as set forth in the
Prospectus, and all of the issued shares of capital stock of the Company
(including the Shares being delivered at such

                                      F-9


Time of Delivery) have been duly and validly authorized and issued and are fully
paid and non-assessable; and the Shares conform to the description of the Stock
contained in the Prospectus;

         (iii)  The Company has been duly qualified as a foreign corporation for
the transaction of business and is in good standing under the laws of each other
jurisdiction in which it owns or leases properties or conducts any business so
as to require such qualification or is subject to no material liability or
disability by reason of failure to be so qualified in any such jurisdiction
(such counsel being entitled to rely in respect of the opinion in this clause
upon opinions of local counsel, published compilations of the laws of such state
and in respect of matters of fact upon certificates of officers of the Company,
provided that such counsel shall state that they believe that both you and they
are justified in relying upon such opinions and certificates);

         (iv)   Each subsidiary of the Company has been duly incorporated and is
validly existing as a corporation in good standing under the laws of its
jurisdiction of incorporation; and all of the issued shares of capital stock of
each such subsidiary have been duly and validly authorized and issued, are fully
paid and non-assessable, and (except for directors' qualifying shares) are owned
directly or indirectly by the Company, free and clear of all liens,
encumbrances, equities or claims (such counsel being entitled to rely in respect
of the opinion in this clause upon opinions of local counsel and in respect to
matters of fact upon certificates of officers of the Company or its
subsidiaries, provided that such counsel shall state that they believe that both
you and they are justified in relying upon such opinions and certificates);

         (v)    The Company and its subsidiaries have good and marketable title
in fee simple to all real property owned by them, in each case free and clear of
all liens, encumbrances and defects except such as (a) are described in the
Prospectus or (b) do not materially affect the value of such property and do not
interfere with the use made and proposed to be made of such property by the
Company and its subsidiaries in a manner 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 real property and buildings held
under lease by the Company and its subsidiaries are held by them under valid,
subsisting and enforceable leases with such exceptions as are not material and
do not interfere with the use made and proposed to be made of such property and
buildings by the Company and its subsidiaries (in giving the opinion in this
clause, such counsel may state that no examination of record titles for the
purpose of such opinion has been made, and that they are relying upon a general
review of the titles of the Company and its subsidiaries, upon opinions of local
counsel and abstracts, reports and policies of title companies rendered or
issued at or subsequent to the time of acquisition of such property by the
Company or its subsidiaries, upon opinions of counsel to the lessors of such
property and, in respect to matters of fact, upon certificates of officers of
the Company or its subsidiaries, provided that such counsel shall state that
they believe that both you and they are justified in relying upon such opinions,
abstracts, reports, policies and certificates);

         (vi)   To such counsel's knowledge and other than as set forth in the
Prospectus, there are no legal or governmental proceedings pending to which the
Company or any of its subsidiaries is a party or of which any property of the
Company or any of its subsidiaries is the subject and, to such counsel's
knowledge, no such proceedings are threatened or contemplated by governmental
authorities or threatened by others;

         (vii)  This Agreement has been duly authorized, executed and delivered
by the Company;

                                      F-10


         (viii)  The issue and sale of the Shares being delivered at such Time
of Delivery by the Company and the compliance by the Company with all of the
provisions of this Agreement and the consummation of the transactions herein
contemplated will not conflict with or result in a breach or violation of any of
the terms or provisions of, or constitute a default under, any indenture,
mortgage, deed of trust, loan agreement or other agreement or instrument known
to such counsel to which the Company or any of its subsidiaries is a party or by
which the Company or any of its subsidiaries is bound or to which any of the
property or assets of the Company or any of its subsidiaries is subject, nor
will such action result in any violation of the provisions of the Certificate of
Incorporation or By-laws of the Company or any statute or any order, rule or
regulation known to such counsel of any court or governmental agency or body
having jurisdiction over the Company or any of its subsidiaries or any of their
properties;

         (ix)    No consent, approval, authorization, order, registration or
qualification of or with any such court or governmental agency or body is
required for the issue and sale of the Shares or the consummation by the Company
of the transactions contemplated by this Agreement, except the registration
under the Act of the Shares, and such consents, approvals, authorizations,
registrations or qualifications as may be required under state securities or
Blue Sky laws in connection with the purchase and distribution of the Shares by
the Underwriters;

         (x)     Neither the Company nor any of its subsidiaries is in violation
of its Certificate of Incorporation or By-laws or in default in the performance
or observance of any material obligation, agreement, covenant or condition
contained in any indenture, mortgage, deed of trust, loan agreement, lease or
other agreement or instrument to which it is a party or by which it or any of
its properties may be bound;

         (xi)    The statements set forth in the Prospectus under the caption
"Description of Capital Stock", insofar as they purport to constitute a summary
of the terms of the Stock are accurate, complete and fair;

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

         (xiii)  The Registration Statement and the Prospectus and any further
amendments and supplements thereto made by the Company prior to such Time of
Delivery (other than the financial statements and related schedules therein, as
to which such counsel need express no opinion) comply as to form in all material
respects with the requirements of the Act and the rules and regulations
thereunder.

         (xiv)   Although they do not assume any responsibility for the
accuracy, completeness or fairness of the statements contained in the
Registration Statement or the Prospectus, except for those referred to in the
opinion in subsection (xi) of this section 7(c), they have no reason to believe
that, as of its effective date, the Registration Statement or any further
amendment thereto made by the Company prior to such Time of Delivery (other than
the financial statements and related schedules therein, as to which such counsel
need express no opinion) contained an untrue statement of a material fact or
omitted to state a material fact required to be stated therein or necessary to
make the statements therein not misleading or that, as of its date, the
Prospectus or any further amendment or supplement thereto made by the Company
prior to such Time of Delivery (other than the financial statements and related
schedules therein, as to which such counsel need express no opinion) contained
an untrue statement of a material fact or omitted to state a material fact
necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading or that, as of such Time of Delivery,
either the Registration Statement or the Prospectus

                                      F-11


or any further amendment or supplement thereto made by the Company prior to such
Time of Delivery (other than the financial statements and related schedules
therein, as to which such counsel need express no opinion) contains an untrue
statement of a material fact or omits to state a material fact necessary to make
the statements therein, in the light of the circumstances under which they were
made, not misleading; and they do not know of any amendment to the Registration
Statement required to be filed or of any contracts or other documents of a
character required to be filed as an exhibit to the Registration Statement or
required to be described in the Registration Statement or the Prospectus which
are not filed or described as required;

     (d) On the date of the Prospectus at a time prior to the execution of this
Agreement, at 9:30 a.m., New York City time, on the effective date of any post-
effective amendment to the Registration Statement filed subsequent to the date
of this Agreement and also at each Time of Delivery, Ernst & Young, LLP shall
have furnished to you a letter or letters, dated the respective dates of
delivery thereof, in form and substance satisfactory to you, to the effect set
forth in Annex I hereto (the executed copy of the letter delivered prior to the
execution of this Agreement is attached as Annex I(a) hereto and a draft of the
form of letter to be delivered on the effective date of any post-effective
amendment to the Registration Statement and as of each Time of Delivery is
attached as Annex I(b) hereto);

     (e) (i) Neither the Company nor any of its subsidiaries shall have
sustained since the date of the latest audited financial statements included in
the Prospectus any loss or interference with its business from fire, explosion,
flood or other calamity, whether or not covered by insurance, or from any labor
dispute or court or governmental action, order or decree, otherwise than as set
forth or contemplated in the Prospectus, and (ii) since the respective dates as
of which information is given in the Prospectus there shall not have been any
change in the capital stock or long-term debt of the Company or any of its
subsidiaries or any change, or any development involving a prospective change,
in or affecting the general affairs, management, financial position,
stockholders' equity or results of operations of the Company and its
subsidiaries, otherwise than as set forth or contemplated in the Prospectus, the
effect of which, in any such case described in clause (i) or (ii), is in the
judgment of the Representatives so material and adverse as to make it
impracticable or inadvisable to proceed with the public offering or the delivery
of the Shares being delivered at such Time of Delivery on the terms and in the
manner contemplated in the Prospectus;

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

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

                                      F-12


     (h) The Shares to be sold at such Time of Delivery shall have been duly
listed for quotation on NASDAQ;

     (i) The Company has obtained and delivered to the Underwriters executed
copies of an agreement from each stockholder, substantially to the effect set
forth in Subsection 1(p) hereof in form and substance satisfactory to you;

     (j) The Company shall have complied with the provisions of Section 5(c)
hereof with respect to the furnishing of prospectuses on the New York Business
Day next succeeding the date of this Agreement; and

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

     (l) [Company IP Counsel], special counsel for the Company, shall have
furnished to you its written opinion dated such Time of Delivery, in form and
substance satisfactory to you, to the effect that:

         (i)   To such counsel's knowledge, except as generally described in the
Prospectus, the Company has not received any notice of infringement or of
conflict with rights or claims of others with respect to any intellectual
property.  Except as generally described in the Prospectus, nothing has come to
such counsel's attention that has led them to believe that any patents of others
are infringed by the processes or practices of the Company, or by the
manufacture, use or sale of the Company's products.

         (ii)  To such counsel's knowledge, except (a) in connection with
assertions or inquiries made by Patent Office examiners in the ordinary course
of the prosecution of patent applications in the Patent Office or (b) as may be
generally described in the Prospectus, there is not pending or threatened in
writing any action, suit, proceeding or claim (x) challenging the validity or
scope of the patent applications held by or licensed to the Company or (y)
asserting that any patent is infringed by the processes or practices of the
Company, or by the manufacture, use or sale of the Company's products.

         (iii) Such counsel, as patent counsel to the Company, except as may be
generally described in the Prospectus, do not know of any pending or threatened
litigation or any governmental proceeding, statute or regulation which would
affect the Company's intellectual property rights to patents or patent
applications, or under any instrument or other document relating thereof.

         (iv)  Such counsel believes that the descriptions relating to patents
and patent applications with respect to all patent matters under "Risk Factors -
Any Inability to Adequately Protect Our Proprietary Technologies Could Harm Our
Competitive Position", "Risk Factors - Litigation or Other Proceedings or Third
Party Claims of Intellectual Property Infringement Could Require Us to Spend
Time and Money and Could Shut Down Some of Our Operations", Business - The
Maxygen Solution", "Business - Maxygen's Molecular Breeding Technologies" and
"Business - Intellectual Property and Technology Licenses" in the Prospectus are
accurate and fairly present the information shown, and such counsel does not
know of any instrument or other document relating to patents or patent
applications required to be summarized or described therein or to be filed as an
exhibit thereto which is not so summarized, described or filed.

                                      F-13


         (v) Such counsel does not believe that the statements relating to
patents, patent applications and patent matters under "Risk Factors - Any
Inability to Adequately Protect Our Proprietary Technologies Could Harm Our
Competitive Position", "Risk Factors - Litigation or Other Proceedings or Third
Party Claims of Intellectual Property Infringement Could Require Us to Spend
Time and Money and Could Shut Down Some of Our Operations", Business - The
Maxygen Solution", "Business - Maxygen's Molecular Breeding Technologies" and
"Business - Intellectual Property and Technology Licenses" in the Registration
Statement such counsel reviewed, contained any untrue statement of a material
fact or omitted to state any material fact which was required to be stated
therein from a patent law perspective or necessary in order to make the
statements therein not misleading.

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

     (b) Each Underwriter will indemnify and hold harmless the Company against
any losses, claims, damages or liabilities to which the Company may become
subject, under the Act or otherwise, insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) arise out of or are based upon an
untrue statement or alleged untrue statement of a material fact contained in any
Preliminary Prospectus, the Registration Statement or the Prospectus, or any
amendment or supplement thereto, or arise out of or are based upon the omission
or alleged omission to state therein a material fact 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 any Preliminary
Prospectus, the Registration Statement or the Prospectus or any such amendment
or supplement in reliance upon and in conformity with written information
furnished to the Company by such Underwriter through Goldman, Sachs & Co.
expressly for use therein; and will reimburse the Company for any legal or other
expenses reasonably incurred by the Company in connection with investigating or
defending any such action or claim as such expenses are incurred.

     (c) Promptly after receipt by an indemnified party under subsection (a) or
(b) above of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party under such subsection, notify the indemnifying party in writing of the
commencement thereof; but the omission so to notify the indemnifying party shall
not relieve it from any liability which it may have to any indemnified party
otherwise than under such subsection.  In case any such action shall be brought
against any indemnified party and it shall notify the indemnifying party of the
commencement thereof, the indemnifying party shall be entitled to

                                      F-14


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

     (d) If the indemnification provided for in this Section 8 is unavailable to
or insufficient to hold harmless an indemnified party under subsection (a) or
(b) above in respect of any losses, claims, damages or liabilities (or actions
in respect thereof) referred to therein, then each indemnifying party shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages or liabilities (or actions in respect thereof)
in such proportion as is appropriate to reflect the relative benefits received
by the Company on the one hand and the 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 or if the indemnified
party failed to give the notice required under subsection (c) above, then each
indemnifying party shall contribute to such amount paid or payable by such
indemnified party in such proportion as is appropriate to reflect not only such
relative benefits but also the relative fault of the Company on the one hand and
the Underwriters on the other in connection with the statements or omissions
which resulted in such losses, claims, damages or liabilities (or actions in
respect thereof), as well as any other relevant equitable considerations.  The
relative benefits received by the Company on the one hand and the Underwriters
on the other shall be deemed to be in the same proportion as the total net
proceeds from the offering (before deducting expenses) received by the Company
bear to the total underwriting discounts and commissions received by the
Underwriters, in each case as set forth in the table on the cover page of the
Prospectus.  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 the Underwriters
agree that it would not be just and equitable if contributions pursuant to this
subsection (d) 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 subsection (d).  The amount paid or payable by an indemnified
party as a result of the losses, claims, damages or liabilities (or actions in
respect thereof) referred to above in this subsection (d) shall be deemed to
include any legal or other expenses reasonably incurred by such indemnified
party in connection with investigating or defending any such action or claim.
Notwithstanding the provisions of this subsection (d), no Underwriter shall be
required to contribute any amount in excess of the amount by which the total
price at which the Shares underwritten by it and distributed to the public were
offered to the public exceeds the amount

                                      F-15


of any damages which such Underwriter has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission. No person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation. The Underwriters'
obligations in this subsection (d) to contribute are several in proportion to
their respective underwriting obligations and not joint.

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

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

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

     (c) If, after giving effect to any arrangements for the purchase of the
Shares of a defaulting Underwriter or Underwriters by you and the Company as
provided in subsection (a) above, the aggregate number of such Shares which
remains unpurchased exceeds one-eleventh of the aggregate number of all the
Shares to be purchased at such Time of Delivery, or if the Company shall not
exercise the right described in subsection (b) above to require non-defaulting
Underwriters to purchase Shares of a defaulting Underwriter or Underwriters,
then this Agreement (or, with respect to the Second Time of Delivery, the
obligations of the Underwriters to purchase and of the Company to

                                      F-16


sell the Optional Shares) shall thereupon terminate, without liability on the
part of any non-defaulting Underwriter or the Company, except for the expenses
to be borne by the Company and the Underwriters as provided in Section 6 hereof
and the indemnity and contribution agreements in Section 8 hereof; but nothing
herein shall relieve a defaulting Underwriter from liability for its default.

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

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

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

     All statements, requests, notices and agreements hereunder shall be in
writing, and if to the Underwriters shall be delivered or sent by mail, telex or
facsimile transmission to you as the representatives in care of Goldman, Sachs &
Co., 32 Old Slip, 21st Floor, New York, New York  10005, Attention: Registration
Department; and if to the Company shall be delivered or sent by mail to the
address of the Company set forth in the Registration Statement, Attention:
Secretary; provided, however, that any notice to an Underwriter pursuant to
Section 8(c) hereof shall be delivered or sent by mail, telex or facsimile
transmission to such Underwriter at its address set forth in its Underwriters'
Questionnaire, or telex constituting such Questionnaire, which address will be
supplied to the Company by you upon request.  Any such statements, requests,
notices or agreements shall take effect upon receipt thereof.

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

     14.  Time shall be of the essence of this Agreement.  As used herein, the
term "business day" shall mean any day when the Commission's office in
Washington, D.C.  is open for business.

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

                                      F-17


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

                                      F-18


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

                                    Very truly yours,

                                    Maxygen, Inc.

                                    By:
                                       ..................................
                                      Name:
                                      Title:

Accepted as of the date hereof:

Goldman, Sachs & Co.
BancBoston Robertson Stephens
Invemed Associates

By:
   ...............................
         Goldman, Sachs & Co.

 On behalf of each of the Underwriters

                                      F-19




                                  SCHEDULE I
                                                                         Number of Optional
                                                                           Shares to be
                                                      Total Number of      Purchased if
                                                       Firm Shares        Maximum Option
                          Underwriter                to be Purchased        Exercised
                          -----------                ---------------    -------------------
                                                                  
Goldman, Sachs & Co............................
BancBoston Robertson Stephens..................
Invemed Associates.............................


                                                     ---------------    -------------------
                    Total......................
                                                     ===============    ===================


                                      F-20