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                                                                   Exhibit 10.33



                              CONSULTING AGREEMENT



John P. Walker
126 Isabella Avenue
Atherton, CA 94027                                               January 1, 2001

Dear John:

     Microcide Pharmaceuticals, Inc. (the "Company") wishes to obtain your
services as a consultant. This letter shall constitute an agreement between you
and the Company, and contains all the terms and conditions relating to the
performance of such services.

     1.   Term and Termination. This agreement shall become effective on January
1, 2001 and terminate on the earlier of the date on which you: (1) cease to
serve on the Company's Board of Directors; or (2) cease to provide services to
the Company under this agreement. This agreement may be terminated either by you
or the Company at any time, subject to the provisions of Paragraph 14.

     2.   Consulting. During the term of this agreement, you will provide
consulting services as may be reasonably requested by the Chief Executive
Officer of the Company. Nominally, you agree to provide consulting services up
to a half-time basis, consistent with the direction of the Company's Board of
Directors.

     3.   Consideration. As consideration for your services and other
obligations, the Company agrees to: (i) pay you at the rate of $15,000.00 per
month, and (ii) grant an option to purchase 75,000 shares of the Common Stock of
the Company under the terms as set forth in Exhibit A.

     4.   Support. As additional consideration for your services hereunder, the
Company will provide you with such support facilities and space as may be
required in the Company's judgment to enable you to properly perform your
services hereunder.

     5.   Expenses. You will be reimbursed for reasonable travel and other
out-of-pocket expenses incurred by you in connection with your services under
this agreement, provided that you provide receipts and an invoice on a monthly
basis and obtain prior approval of the Chief Executive Officer of the Company
for any significant expenses. Such reimbursements will be paid within fifteen
(15) days of receipt of the invoice.

     6.   Independent Contractor. Your relationship with the Company will be
that of an independent contractor and not that of an employee. You will not be
eligible for any employee

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benefits, nor will the Company make deductions from payments made to you for
taxes, which will be your responsibility. You agree to indemnify and hold the
Company harmless from any liability for, or assessment of, any such taxes
imposed on the Company by relevant taxing authorities. You will have no
authority to enter into contracts that bind the Company or create obligations on
the part of the Company without the prior written authorization of the Company.

     7.   Reporting. All services to be performed by you will be as agreed
between you and the Chief Executive Officer of the Company, with periodic
reports to the Board of Directors concerning your services performed under this
agreement. The nature and frequency of these reports will be left to the
discretion of the Board of Directors.

     8.   Confidentiality. You shall keep in confidence and shall not disclose
or make available to third parties or make any use of any information or
documents relating to your services under this agreement, the research and
development activities, or to the products, methods of manufacture, trade
secrets, processes, business or affairs or confidential or proprietary
information of the Company (other than information in the public domain through
no fault of your own), except with the prior written consent of the Company or
to the extent necessary in performing tasks assigned to you by the Company.
Within five business days of termination of this agreement, you will return to
the company all documents and other materials related to the services provided
hereunder or furnished to you by the Company at any time. Your obligations under
this Paragraph 8 will survive termination of this agreement.

     9.   Amendment. Any amendment to this agreement must be in writing signed
by you and the Company.

     10.  Notices. All notices, requests and other communications called for by
this agreement shall be deemed to have been given if made in writing and
personally delivered or mailed, postage prepaid, if to you at the address set
forth above and if to the Company at 850 Maude Avenue, Mountain View, California
94043, Attention: Chief Executive Officer, or to such other addresses as either
party shall specify to the other.

     11.  Governing Law. The laws of the State of California shall govern the
validity, performance and construction of this agreement.

     12.  Arbitration. By signing this agreement, you acknowledge and understand
that any disagreement regarding this agreement will be determined by submission
to arbitration as provided by Section 1230 et seq. of the California code of
Civil Procedure, and not by a lawsuit or resort to court process proceedings.
All parties to this Agreement, by entering into it, are giving up any right to
have any such dispute decided in a court before a jury, and instead are
accepting the use of arbitration.

     13.  Prior Agreements. This agreement supersedes all other agreements
between you and the Company.

     14.  Corporate Transaction. In the event of a Corporate Transaction as
defined in Exhibit A that results in the loss of acceleration of vesting of
options in order to permit the

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transaction to be accounted for as a "Pooling of Interests", this agreement
shall be automatically extended for a period of three years, and shall not be
subject to earlier termination unless by mutual consent of the parties hereto.

     If this agreement is satisfactory, you should execute and return the
original and one copy to us, retaining the third copy for your file.

                                       Very truly yours,

                                       By: /s/ James E. Rurka
                                          -----------------------------
                                       Title:  Chief Executive Officer


AGREED AND ACCEPTED:

/s/  John P. Walker
----------------------
Signature

2/13/2001



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                                                                       Exhibit A



                               STOCK OPTION GRANT



1.   Consultant will be granted a non-qualified option to purchase 75,000 shares
     of the Company's Common Stock, at an exercise price of $7.625 per share,
     the closing price for the Company's Common Stock reported by the Nasdaq
     National Stock Market on the day of approval of the grant by the
     Compensation Committee of the Board of Directors.

2.   The option shall have a term of ten (10) years and vest monthly over 4
     years.

3.   Accelerated Vesting: If a Corporate Transaction (as defined below) occurs
     prior to the complete vesting, but in no case after 3 months from the date
     of termination of the Consultant, the option shall immediately vest with
     respect to any remaining unvested shares and be fully exercisable for the
     entire number of shares of the Company's Common Stock underlying the
     option. The term "Corporate Transaction" shall mean (i) a merger,
     reorganization or other transaction (other than a financing) following
     which the shareholders of the Company do not own a majority of the capital
     stock of the surviving corporation; or (ii) the sale of all or
     substantially all of the assets of the Company.

4.   Potential Pooling Transactions: In the event the Company's Board of
     Directors determines that acceleration of vesting of options would preclude
     accounting for a proposed Corporate Transaction involving a Change in
     Control as a "Pooling of Interests," but the Board of Directors otherwise
     desires to approve and account for such transaction as a "Pooling of
     Interests," the acceleration of vesting of options shall be null and void.


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