EXHIBIT 99.02


                             SELLING AGENT AGREEMENT


         THIS SELLING AGENT AGREEMENT (the "Agreement") is entered into as of
this 15th day of July, 2002 by and between Cepheid, a California corporation
(the "Company"), and William Blair & Company, L.L.C. (the "Selling Agent").

                                    RECITALS

         WHEREAS, the Selling Agent is a broker-dealer registered with the
Securities and Exchange Commission and a member of the National Association of
Securities Dealers, Inc.

         WHEREAS, the Company, pursuant to an engagement letter dated June 24,
2002 (the "Engagement Letter"), has retained the Selling Agent as its exclusive
selling agent to provide assistance with the solicitation of purchasers of
common stock of the Company ("Common Stock") in a registered public offering and
the Company and the Selling Agent wish to set forth the terms and conditions
upon which such services will be provided.

         NOW, THEREFORE, in consideration of the mutual promises contained in
this Agreement and other good and valuable consideration, the receipt and
sufficiency of which is acknowledged, the parties, each intending to be legally
bound, hereby agree as follows:

1.       Appointment of Selling Agent.

         The Company hereby appoints the Selling Agent, and, on the basis of the
Company's representations, warranties and covenants contained herein and subject
to the terms and conditions set forth herein, the Selling Agent hereby accepts
such appointment, as the exclusive agent of the Company for the purpose of using
its reasonable best efforts to solicit offers to purchase shares of Common Stock
(the "Shares") having an aggregate public offering price of up to $12,500,000 in
a public offering (the "Offering") pursuant to the Company's Registration
Statement on Form S-3 (File No. 333-75596) (as declared effective by the
Securities and Exchange Commission (the "Commission") on May 29, 2002 and
including all information incorporated by reference therein, the "Registration
Statement"). The Selling Agent shall communicate to the Company each reasonable
offer or indication of interest received by it to purchase Shares. The Company
shall have the sole right to accept offers to purchase the Shares and may reject
any such offer in whole or in part. The Selling Agent shall have the right to
reject, in its discretion reasonably exercised, any offer received by it to
purchase the Shares, in whole or in part, and any such rejection shall not be
deemed a breach of its agreements contained herein. In soliciting offers to
purchase the Shares hereunder, the Selling Agent is acting solely as agent for
the Company, and not as principal. The Selling Agent shall have no liability to
the Company in the event any purchase of Shares by a purchaser whose offer to
purchase Shares has been solicited by the Selling Agent and accepted by the
Company is not consummated for any reason. Under no circumstances will the
Selling Agent be obligated to purchase any Shares for its own account.

2.       Representations and Warranties. The Company hereby represents, warrants
         and agrees as follows:

         (a)      The Company has been duly incorporated and is validly existing
                  as a corporation in good standing under the laws of the State
                  of California, 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, except for such jurisdictions
                  wherein the failure to be so qualified and in good standing
                  would not individually or in the aggregate have a material
                  adverse effect on the business results of operations or
                  financial condition of the Company and its subsidiaries taken
                  as a whole (a "Material Adverse Effect"); 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, 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, except for
                  such jurisdictions wherein the failure to be so qualified and
                  in good standing would not individually or in the aggregate
                  have a Material Adverse Effect. The term "Prospectus" as used
                  herein shall mean the prospectus forming a part of the
                  Registration Statement in the form first filed pursuant to
                  Rule 424(b) under the Securities Act, as amended (the
                  "Securities Act"), as such prospectus is supplemented at the
                  relevant time, including by the final prospectus supplement
                  relating to the Offering (the "Prospectus Supplement") that
                  the Company will file with the Commission pursuant to Rule
                  424(b) under the Securities Act, and including all information
                  incorporated by reference therein.

         (b)      The execution, delivery and performance of this Agreement by
                  the Company and the consummation by the Company of the
                  transactions contemplated hereby have been duly authorized by
                  all necessary corporate action of the Company and the
                  Agreement has been duly executed and delivered by the Company;
                  and this Agreement, when duly executed and delivered by the
                  Selling Agent, will constitute a valid and legally binding
                  instrument of the Company enforceable in accordance with its
                  terms, except as enforcement hereof may be limited by the
                  effect of any applicable bankruptcy, insolvency,
                  reorganization or similar laws or court decisions affecting
                  enforcement of creditors' rights generally and except as
                  enforcement hereof is subject to general principles of equity
                  (regardless of whether enforcement is considered in a
                  proceeding in equity or at law).

         (c)      The Shares have been duly authorized by the Company, and when
                  issued and delivered by the Company against payment therefore
                  as contemplated hereby, the Shares will be validly issued,
                  fully paid and nonassessable, and will conform to the
                  description of the Common Stock contained in the Prospectus.


                                       2

         (d)      The execution and delivery of this Agreement, the consummation
                  by the Company of the transactions herein contemplated and the
                  compliance by the Company with the terms hereof do not and
                  will not violate the Articles of Incorporation (as amended to
                  date) of the Company or the By-Laws (as amended to date) of
                  the Company, 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 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 their properties or
                  assets are subject, or any applicable statute or any order,
                  judgment, decree, rule or regulation of any court or
                  governmental or regulatory agency or body having jurisdiction
                  over the Company or any of its subsidiaries or any of their
                  properties or assets, except where such breach, violation,
                  default or the failure to be in compliance would not
                  individually or in the aggregate have a Material Adverse
                  Effect or adversely affect the ability of the Company to
                  consummate the transactions contemplated hereby; and no
                  consent, approval, authorization, order, registration, filing
                  or qualification of or with any such court or governmental or
                  regulatory agency or body is required for the valid
                  authorization, execution, delivery and performance by the
                  Company of this Agreement, the issuance of the Shares or the
                  consummation by the Company of the other transactions
                  contemplated by this Agreement, except for such consents,
                  approvals, authorizations, registrations or qualifications as
                  may be required under Federal or state securities or "blue
                  sky" laws or in connection with the listing of the Shares on
                  the Nasdaq National Market.

         (e)      The Company meets the requirements for the use of Form S-3
                  under the Securities Act for the primary issuance of
                  securities. The Registration Statement has been declared
                  effective by the Commission and at the time it became
                  effective, and as of the date hereof, the Registration
                  Statement complied and complies with Rule 415 under the
                  Securities Act. No stop order suspending the effectiveness of
                  the Registration Statement has been issued and no proceeding
                  for that purpose has been initiated or, to the Company's
                  knowledge, threatened by the Commission. On the effective date
                  of the Registration Statement, the Registration Statement and
                  the Prospectus fully conformed, and at the Closing Date, the
                  Registration Statement and the Prospectus will fully conform,
                  in all material respects with the applicable provisions of the
                  Securities Act and the applicable rules and regulations of the
                  Commission thereunder; on the effective date of the
                  Registration Statement, the Registration Statement did not,
                  and at the Closing Date, the Registration Statement will not,
                  contain an untrue statement of a material fact or omit to
                  state a material fact required to be stated therein or
                  necessary in order to make the statements therein not
                  misleading; on the effective date of the Registration
                  Statement, the Prospectus did not, and on the date the
                  Prospectus Supplement is filed with the Commission pursuant to
                  Rule 424(b) under the Securities Act and the Closing Date, the
                  Prospectus will not, contain an untrue statement 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; and when filed with the Commission, the documents
                  incorporated by reference in the Registration Statement and
                  the Prospectus, taken as a whole, fully


                                       3

                  conformed or will fully conform in all material respects with
                  the applicable provisions of the Securities Exchange Act of
                  1934, as amended (the "Exchange Act"), and the applicable
                  rules and regulations of the Commission thereunder.

         (f)      The consolidated financial statements and financial schedules
                  of the Company included or incorporated by reference in the
                  Registration Statement and the Prospectus have been prepared
                  in conformity with generally accepted accounting principles
                  (except, with respect to the unaudited consolidated financial
                  statements, for the footnotes and subject to customary audit
                  adjustments) applied on a consistent basis, are consistent in
                  all material respects with the books and records of the
                  Company, and accurately present in all material respects the
                  consolidated financial position, results of operations and
                  cash flow of the Company and its subsidiaries as of and for
                  the periods covered thereby.

         (g)      Neither the Company nor any of its subsidiaries has sustained
                  since the date of the latest audited financial statements
                  included or incorporated by reference 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 disclosed in or
                  contemplated by 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 material
                  change in the capital stock or long-term debt of the Company
                  or any of its subsidiaries, the Company and its subsidiaries
                  have not incurred any material liabilities or obligations,
                  direct or contingent, nor entered into any material
                  transactions not in the ordinary course of business and there
                  has not been any material adverse change in or affecting the
                  general affairs, management, financial position, stockholders'
                  equity or results of operations of the Company and its
                  subsidiaries considered as a whole, otherwise than as
                  disclosed or incorporated by reference in or contemplated by
                  the Prospectus.

         (h)      Other than as set forth or incorporated by reference in the
                  Prospectus, there are no legal, governmental or regulatory
                  proceedings pending to which the Company or any of its
                  subsidiaries is a party or of which any material property of
                  the Company or any of its subsidiaries is the subject which,
                  taking into account the likelihood of the outcome, the damages
                  or other relief sought and other relevant factors, would
                  individually or in the aggregate reasonably be expected to
                  have a Material Adverse Effect or adversely affect the ability
                  of the Company to consummate the transactions contemplated
                  hereby; to the best of the Company's knowledge, no such
                  proceedings are threatened or contemplated by governmental or
                  regulatory authorities or threatened by others.

         (i)      There are no holders of securities of the Company having
                  preemptive rights to purchase Common Stock. There are no
                  holders of securities of the Company having rights to
                  registration thereof whose securities have not been previously
                  registered or who have not waived such rights with respect to
                  the registration of the Company's securities on the
                  Registration Statement.


                                       4

         (j)      The Company has not taken and will not take, directly or
                  indirectly, any action designed to, or which has constituted,
                  or which might reasonably be expected to cause or result,
                  under the Exchange Act or otherwise, in stabilization or
                  manipulation of the price of any security of the Company to
                  facilitate the sale or resale of the Shares.

         (k)      The Company together with its subsidiaries owns and possesses
                  all right, title and interest in and to, or has duly licensed
                  from third parties, all patents, patent rights, trade secrets,
                  inventions, know-how, trademarks, trade names, copyrights,
                  service marks and other proprietary rights ("Intellectual
                  Property") material to the business of the Company and each of
                  its subsidiaries taken as a whole. Neither the Company nor any
                  of its subsidiaries has received any notice of infringement,
                  misappropriation or conflict from any third party as to such
                  that has not been resolved or disposed of and to the Company's
                  knowledge, neither the Company nor any of its subsidiaries has
                  infringed, misappropriated or otherwise conflicted with
                  Intellectual Property of any third parties, which
                  infringement, misappropriation or conflict would individually
                  or in the aggregate have a Material Adverse Effect.

         (l)      The conduct of the business of the Company and each of its
                  subsidiaries is in compliance in all respects with applicable
                  federal, state, local and foreign laws and regulations, except
                  where the failure to be in compliance would not individually
                  or in the aggregate have a Material Adverse Effect.

         (m)      The Company is not, and does not intend to conduct its
                  business in a manner in which it would become, an "investment
                  company" as defined in Section 3(a) of the Investment Company
                  Act of 1940, as amended.

3.       Covenants of the Company.  The Company covenants and agrees that:

         (a)      The Company will advise the Selling Agent promptly of the
                  issuance by the Commission of any stop order suspending the
                  effectiveness of the Registration Statement or of the
                  institution of any proceedings for that purpose, or of any
                  notification of the suspension of qualification of the Shares
                  for sale in any jurisdiction or the initiation or threatening
                  of any proceedings for that purpose, and will also advise the
                  Selling Agent promptly of any request of the Commission for
                  amendment or supplement of the Registration Statement or the
                  Prospectus or for additional information.

         (b)      The Company will give the Selling Agent notice of its
                  intention to file or prepare any post-effective amendment to
                  the Registration Statement or any amendment or supplement to
                  the Prospectus and will furnish the Selling Agent with copies
                  of any such amendment or supplement a reasonable amount of
                  time prior to such proposed filing or use, as the case may be,
                  and will not file any such amendment or supplement to which
                  the Selling Agent or its counsel shall reasonably object.

         (c)      The Company will (i) provide the Selling Agent and its
                  counsel, without charge, with copies of the Prospectus, in
                  such numbers as the Selling Agent and its

                                       5

                  counsel may reasonably request, (ii) file with the Commission
                  the Prospectus and Prospectus Supplement in accordance with
                  Rule 424(b) of the Securities Act and (iii) deliver the
                  Prospectus and Prospectus Supplement to purchasers of the
                  Shares in accordance with, and at such time as is required by,
                  the federal securities laws. The Company will also deliver to
                  the Selling Agent such number of copies of the Stock Purchase
                  Agreement (as defined below) as the Selling Agent may
                  reasonably request.

         (d)      If at any time when a prospectus relating to the Shares is
                  required to be delivered under the Securities Act any event
                  occurs as a result of which the Prospectus, including any
                  amendments or supplements, would include an untrue statement
                  of a material fact, or omit to state any material fact
                  required to be stated therein or necessary to make the
                  statements therein, in light of the circumstances under which
                  they were made, not misleading, or if it is necessary at any
                  time to amend the Prospectus, including any amendments or
                  supplements thereto, to comply with the Securities Act, the
                  Company promptly will advise the Selling Agent thereof and
                  subject to Section 3(b), will promptly prepare and file with
                  the Commission an amendment or supplement which will correct
                  such statement or omission or an amendment which will effect
                  such compliance;

         (e)      The Company will cooperate with the Selling Agent in
                  qualifying or registering the Shares for sale under the blue
                  sky laws of such jurisdictions as the Selling Agent
                  designates, and will continue such qualifications in effect so
                  long as reasonably required for the distribution of the
                  Shares; provided, however, that the Company shall not be
                  required to qualify as a foreign corporation or to file a
                  general consent to service of process in any such jurisdiction
                  where it is not currently qualified or where it would be
                  subject to taxation as a foreign corporation.

         (f)      The Company will use the net proceeds received by it from the
                  sale of the Shares in the manner specified in the Prospectus
                  under the caption "Use of Proceeds."

         (g)      The Company will file with the Nasdaq National Market a
                  Notification of Listing of Additional Shares with respect to
                  the Shares within the time period required by the rules of the
                  Nasdaq National Market.

         (h)      The Company agrees not to sell, contract to sell, transfer or
                  otherwise dispose of any Common Stock or securities
                  convertible into, or exercisable or exchangeable for, Common
                  Stock (except for grants of options or stock awards under its
                  current stock option plans and Common Stock issued pursuant to
                  currently outstanding options, warrants or convertible
                  securities or pursuant to the Company's current employee stock
                  purchase plan) for a period of 90 days after the date that the
                  Prospectus Supplement is filed with the Commission without the
                  prior written consent of William Blair & Company, L.L.C. The
                  Company will use reasonable best efforts to cause each of its
                  officers and directors to enter into similar agreements with
                  the Selling Agent.


                                       6

4.       Closing. The terms and conditions, including the purchase price and
         number of Shares, upon which the Shares will be sold will be set forth
         in stock purchase agreements between the Company and the purchasers of
         the Shares, substantially in the form of Appendix A attached hereto
         (the "Stock Purchase Agreements"). The closing of the purchase and sale
         of the Shares shall be on such date set forth in the Stock Purchase
         Agreement (the "Closing Date") and, along with the obligations of the
         Selling Agent to solicit offers to purchase the Shares pursuant to
         Section 1, shall be subject to the accuracy of the representations and
         warranties of the Company contained herein as of the date hereof and as
         of the Closing Date, the performance and observance by the Company of
         all its covenants and agreements contained herein and the following
         conditions:

         (a)      Prior to the Closing Date, no stop order suspending the
                  effectiveness of the Registration Statement shall have been
                  issued and no proceedings for that purpose shall have been
                  instituted or shall be pending or, to the knowledge of the
                  Company or the Selling Agent, shall be contemplated by the
                  Commission.

         (b)      The Prospectus Supplement containing the information
                  concerning the public offering price of the Shares and
                  price-related information shall have been transmitted to the
                  Commission for filing pursuant to Rule 424(b) within the
                  prescribed period and delivered to purchasers of the Shares in
                  accordance with, and at such time as is required by, the
                  federal securities laws.

         (c)      Subsequent to the execution and delivery of this Agreement,
                  there shall not have occurred any change, or any development
                  involving a prospective change, in or affecting particularly
                  the business or properties of the Company or its subsidiaries,
                  whether or not arising in the ordinary course of business,
                  which, in the judgment of the Selling Agent, makes it
                  impractical or inadvisable to proceed with the public offering
                  or sale of the Shares as contemplated hereby.

         (d)      There shall have been furnished to the Selling on the Closing
                  Date:

                  (i)      An opinion of Fenwick & West LLP, counsel for the
                           Company, addressed to the Selling Agent and dated the
                           Closing Date, to the effect that:

                                    (1) the Company has been duly incorporated
                           and is validly existing as a corporation in good
                           standing under the laws of the State of California
                           with corporate power and authority to own its
                           properties and conduct its business as described in
                           the Prospectus; and, to such counsel's knowledge, the
                           Company is not required to be qualified to do
                           business as a foreign corporation under the
                           corporation law of any jurisdiction, except where the
                           failure to so qualify would individually or in the
                           aggregate not have a Material Adverse Effect;

                                    (2) an opinion to the same general effect as
                           clause (1) in respect of each significant subsidiary
                           of the Company, as such term is defined in Regulation
                           S-X (each, a "Subsidiary");


                                       7

                                    (3) all of the issued and outstanding
                           capital stock of each Subsidiary has been duly
                           authorized, validly issued and is fully paid and
                           nonassessable, and, except as disclosed in the
                           Registration Statement or Prospectus, to such
                           counsel's knowledge, the Company owns directly or
                           indirectly 100 percent of the outstanding capital
                           stock of each Subsidiary;

                                    (4) the authorized capital stock of the
                           Company conforms as to legal matters in all material
                           respects to the description thereof incorporated by
                           reference in the Prospectus;

                                    (5) based solely on a letter from the Staff
                           of the Commission dated May 29, 2002 and on the oral
                           advice to such counsel from the Staff of the
                           Commission, the Registration Statement has become
                           effective under the 1933 Act, and, to the knowledge
                           of such counsel, 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 contemplated under the
                           Securities Act, and the Registration Statement and
                           the Prospectus (in each case, except for the
                           financial statements and other financial data
                           included or incorporated by reference therein as to
                           which such counsel expresses no opinion) comply as to
                           form in all material respects with the requirements
                           of the Securities Act; the descriptions of statutes,
                           legal and governmental proceedings and contracts and
                           other documents in: (i) the Registration Statement
                           and the Prospectus under the captions "Risks Related
                           to Our Business," "Legal Ownership of Securities" and
                           "Plan of Distribution," (ii) the Company's Annual
                           Report on Form 10-K for the fiscal year ended
                           December 31, 2001 under the captions "Business -
                           Collaborations," "Business - Intellectual Property"
                           and "Business - Risk Factors," and (iii) such other
                           items that may appear on any Form 8-K filed by the
                           Company from the date hereof up to and through the
                           Closing Date are accurate and fairly present the
                           information required to be shown with respect to such
                           statutes, legal and governmental proceedings and
                           contracts and other documents; and such counsel does
                           not know of any legal or governmental proceedings
                           required to be described in the Registration
                           Statement or Prospectus which are not described as
                           required, nor of any contracts or documents of a
                           character required to be described in the
                           Registration Statement or Prospectus or to be filed
                           as exhibits to the Registration Statement which are
                           not described and filed, as required;

                                    (6) the Shares have been duly authorized
                           and, when issued and delivered against payment
                           therefore in accordance with the terms of the Stock
                           Purchase Agreements, will be validly issued, fully
                           paid and nonassessable;

                                    (7) this Agreement and the Stock Purchase
                           Agreements and the performance of the Company's
                           obligations hereunder and thereunder have been duly
                           authorized by all necessary corporate action and this
                           Agreement

                                       8

                           and the Stock Purchase Agreements have been duly
                           executed and delivered by and on behalf of the
                           Company, and are legal, valid and binding agreements
                           of the Company, except as enforceability of the same
                           may be limited by bankruptcy, insolvency,
                           reorganization, moratorium or other similar laws
                           affecting creditors' rights and by the exercise of
                           judicial discretion in accordance with general
                           principles applicable to equitable and similar
                           remedies and except as to those provisions relating
                           to indemnities for liabilities arising under the
                           Securities Act as to which no opinion need be
                           expressed; and no approval, authorization or consent
                           of any public board, agency, or instrumentality of
                           the United States or of the State of California is
                           necessary in connection with the issue or sale of the
                           Shares by the Company pursuant to this Agreement and
                           the Stock Purchase Agreements (other than under
                           applicable blue sky laws);

                                    (8) the execution and performance of this
                           Agreement and the Stock Purchase Agreements does not
                           violate any of the provisions of, or result in a
                           default under, any agreement, franchise, license,
                           indenture, mortgage, deed of trust, or other
                           instrument of the Company or any of its subsidiaries
                           or by which the property of any of them is bound that
                           (a) has been listed as an exhibit to the Registration
                           Statement or any Exchange Act document or report
                           incorporated by reference therein or (b) is listed on
                           Attachment C to such opinion, in each case where such
                           violation or default would be material to the Company
                           and its subsidiaries taken as a whole; or violate any
                           of the provisions of the charter or bylaws of the
                           Company or, so far as is known to such counsel,
                           violate any statute, order, rule or regulation of any
                           United States federal or California or Illinois state
                           regulatory or governmental body having jurisdiction
                           over the Company or any of its subsidiaries;

                                    (9) all documents incorporated by reference
                           in the Prospectus, when they were filed with the
                           Commission, complied as to form in all material
                           respects with the requirements of the Exchange Act;

                           In addition, such counsel shall confirm that during
                           the course of the preparation of the Registration
                           Statement and the Prospectus, it participated in
                           conferences with officers and other representatives
                           of the Company, Selling Agent's counsel (with respect
                           to the Prospectus) and the independent public
                           accountants of the Company, at which conferences the
                           contents of the Registration Statement and the
                           Prospectus and other related matters were discussed.
                           Although such counsel shall not pass upon and shall
                           not assume responsibility for, nor has it verified,
                           the accuracy, completeness or fairness of the
                           statements contained in the Registration Statement or
                           the Prospectus, such counsel will confirm that
                           nothing has come to its attention that causes it to
                           believe that, as of its effective date, the
                           Registration Statement (other than financial
                           statements and any financial data and schedules
                           included therein, as to each of which such counsel
                           expresses no belief) contained an untrue statement of
                           a material

                                       9

                  fact or omitted to state a material fact necessary to make the
                  statements therein not misleading or that, as of its date, the
                  Prospectus (other than financial statements and any financial
                  data and schedules included therein, as to each of which such
                  counsel expresses no belief) contained an untrue statement of
                  a material fact or omitted to state a material fact necessary
                  to make the statements therein, in light of the circumstances
                  under which they were made, not misleading or that, as of the
                  date of such counsel's opinion, either the Registration
                  Statement or the Prospectus (other than financial statements
                  and any financial data and schedules included therein, as to
                  each of which such counsel expresses no belief) contains an
                  untrue statement of a material fact or omits to state a
                  material fact necessary to make the statements therein, in
                  light of the circumstances under which they were made (in the
                  case of the Prospectus), not misleading.

                  (ii)     An opinion of Townsend and Townsend and Crew, special
                           counsel to the Company with respect to Intellectual
                           Property, addressed to the Selling Agent and dated
                           the Closing Date, to the effect that:

                                    (1) To the best of such counsel's knowledge,
                           except as described in the Prospectus, (A) the
                           Company has valid license rights or clear title to
                           the Intellectual Property referenced in the
                           Prospectus, and there are no rights of third parties
                           to any such Intellectual Property; (B) there is no
                           infringement or other violation by third parties of
                           any of the Intellectual Property of the Company
                           referenced in the Prospectus; (C) the Company has not
                           received notice of any claim of infringement of any
                           patents held by third parties; (D) there is no
                           pending or threatened action, suit, proceeding or
                           claim by governmental authorities or others that the
                           Company is infringing a patent; and (E) there is no
                           pending or threatened legal or administrative
                           proceeding relating to patents and patent
                           applications of the Company, other than proceedings
                           initiated by the Company before the United Sates
                           Patent and Trademark office and the patent offices of
                           certain foreign jurisdictions which are in the
                           ordinary course of prosecution;

                                    (2) to the best of such counsel's knowledge,
                           the patent applications of the Company presently on
                           file disclose patentable subject matter, and such
                           counsel is not aware of any inventorship challenges,
                           any interference which has been declared or provoked,
                           or any other material fact with respect to the patent
                           applications of the Company presently on file that
                           (A) would preclude the issuance of patents with
                           respect to such applications, or (B) would lead such
                           counsel to conclude that such patents, when issued,
                           would not be valid and enforceable in accordance with
                           applicable regulations; and

                                    (3) the statements in the Registration
                           Statement and the Prospectus referencing Intellectual
                           Property matters, insofar as such statements
                           constitute summaries of legal matters, contracts,
                           agreements,

                                       10

                           documents or proceedings referred to therein, or
                           refer to statements of law or legal conclusions, are
                           in all material respects accurate and complete
                           statements or summaries of the matters therein set
                           forth. Nothing has come to such counsel's attention
                           that causes them to believe that such above described
                           portions of the Registration Statement, at the time
                           such Registration Statement became effective or as of
                           the Closing Date, contained or contains 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 such above described portions of
                           the Prospectus, at the date of the Prospectus or as
                           of the Closing Date contained or contains an untrue
                           statement of material fact or omitted to state a
                           material fact required to be stated therein or
                           necessary to make the statements therein, in light of
                           the circumstances under which they were made, not
                           misleading.

                  (iii)    A certificate of the chief executive officer and the
                           principal financial officer of the Company, dated the
                           Closing Date, to the effect that:

                                    (1) the representations and warranties of
                           the Company set forth in Section 2 of this Agreement
                           are true and correct in all material respects as of
                           the date of this Agreement and as of the Closing
                           Date, 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 such
                           Closing Date; and

                                    (2) the Commission has not issued an order
                           preventing or suspending the use of the Registration
                           Statement or the Prospectus; no stop order suspending
                           the effectiveness of the Registration Statement has
                           been issued; and to the knowledge of the respective
                           signers, no proceedings for that purpose have been
                           instituted or are pending or contemplated under the
                           Securities Act.

                  (iv)     At the time Stock Purchase Agreements are executed
                           and also on the Closing Date, there shall be
                           delivered to the Selling Agent a letter addressed to
                           the Selling Agent, from Ernst & Young LLP,
                           independent accountants, the first letter to be dated
                           the date of the Stock Purchase Agreements and the
                           second letter to be dated the Closing Date, each in
                           the form heretofore approved by Katten Muchin Zavis
                           Rosenman, counsel for the Selling Agent.

                  (v)      Such further certificates and documents as the
                           Selling Agent may reasonably request.

           All such opinions, certificates, letters and documents shall be in
           compliance with the provisions hereof only if they are satisfactory
           to the Selling Agent and to Katten Muchin Zavis Rosenman, counsel for
           the Selling Agent, which approval shall not be unreasonably withheld.


                                       11

5.       Compensation.

         In consideration of the Selling Agent's execution of this Agreement and
for the performance of its services hereunder, the Selling Agent shall receive
from the Company, on the Closing Date in immediately available funds, a fee in
an amount equal to 6.0% of the aggregate public offering price of the Shares
issued and sold on the Closing Date.

6.       Payment of Expenses.

         Whether or not the transactions contemplated hereunder are consummated
or this Agreement becomes effective as to all of its provisions or is
terminated, the Company agrees to pay (i) all costs, fees and expenses incurred
in connection with the performance of the Company's obligations hereunder,
including without limiting the generality of the foregoing, all fees and
expenses of legal counsel for the Company and of the Company's independent
accountants, all costs and expenses incurred in connection with the preparation,
printing, filing and distribution of each preliminary prospectus and the
Prospectus, this Agreement and the Stock Purchase Agreements and (ii) all fees
and expenses of the Company's transfer agent, printing of the certificates for
the Shares and all transfer taxes, if any, with respect to the sale and delivery
of the Shares. The Company will reimburse the Selling Agent for reasonable
out-of-pocket expenses (including reasonable fees and expenses of its counsel
and any other independent experts retained by the Selling Agent at the Company's
request and pre-approved by Company in writing) reasonably incurred by it in
connection with its engagement hereunder, up to a limit of $50,000. Expenses in
excess of $50,000 will be subject to the prior written approval of the Company.
Such reimbursement will be payable promptly upon submission by the Selling Agent
of statements to the Company.

7.       Indemnification.

         (a)      The Company hereby agrees to indemnify and hold harmless the
                  Selling Agent and each of the Other Indemnified Parties (as
                  defined below) to the fullest extent permitted by law, from
                  and against any and all losses, claims, damages, obligations,
                  penalties, judgments, awards, costs, disbursements and
                  liabilities (including amounts paid in settlement)
                  (collectively, "Losses") and expenses (including, without
                  limitation, all reasonable fees and expenses of the Selling
                  Agent's and each of the Other Indemnified Parties' counsel and
                  all of the Selling Agent's and each of the Other Indemnified
                  Parties' reasonable travel and other out-of-pocket expenses
                  incurred at the Company's request or otherwise incurred in
                  connection with the investigation of any pending or threatened
                  claims or the preparation for, the defense of, or the
                  furnishing of evidence in, any pending or threatened
                  litigation, investigation or proceedings, whether or not the
                  Selling Agent or any Other Indemnified Party is a party
                  thereto) (collectively, "Expenses") based upon, arising out of
                  or in any way relating to (a) oral or written information
                  (including information contained in or omitted from the
                  Registration Statement or the Prospectus) provided by the
                  Company to the Selling Agent or any party to the transactions
                  contemplated hereby, (b) action taken or omitted to be taken
                  by the Company or action taken or omitted to be taken by the
                  Selling Agent at the request of the Company or with the
                  Company's consent, (c) the

                                       12

                  transactions contemplated hereby or (d) the Selling Agent's
                  engagement hereunder; provided that the Company will have no
                  obligation to indemnify and hold harmless the Selling Agent or
                  any of the Other Indemnified Parties pursuant to this Section
                  7(a) in respect of any Losses or Expenses which are finally
                  judicially determined to have resulted primarily and directly
                  from the gross negligence or bad faith of the Selling Agent in
                  fulfilling its duties hereunder. The Company also agrees that
                  neither the Selling Agent nor any of the Other Indemnified
                  Parties shall have any liability (whether direct or indirect,
                  in contract or tort or otherwise) to the Company for or in
                  connection with such engagement, except for any Losses or
                  Expenses which are finally judicially determined to have
                  resulted primarily from the Selling Agent's gross negligence
                  or bad faith in fulfilling its duties hereunder, and the
                  Selling Agent shall promptly refund any Losses or Expenses
                  previously paid by the Company in the event of such final
                  judicial determination. Expenses will be reimbursed or
                  advanced when and as incurred promptly upon submission by the
                  Selling Agent of statements to the Company. The Other
                  Indemnified Parties will mean and include (i) the Selling
                  Agent's affiliates, (ii) the respective members, principals,
                  partners, directors, officers, agents and employees of and
                  counsel to the Selling Agent and its affiliates, (iii) each
                  other person, if any, controlling the Selling Agent or any of
                  its affiliates and (iv) the successors, assigns, heirs and
                  personal representatives of any of the foregoing.

         (b)      Promptly after receipt by the Selling Agent or Other
                  Indemnified Party of service of any complaint or the
                  commencement of any action or proceeding with respect to which
                  indemnification is being sought hereunder, the Selling Agent
                  or such Other Indemnified Party will notify the Company in
                  writing of such complaint or the commencement of such action
                  or proceeding, but failure to so notify the Company will
                  relieve the Company from the obligation to indemnify the
                  Selling Agent or such Other Indemnified Party only if and only
                  to the extent that such failure results in the forfeiture by
                  the Company of substantial rights and defenses, and will not
                  in any event relieve the Company from any other obligation or
                  liability that the Company may have to the Selling Agent or
                  any Other Indemnified Party otherwise than in accordance with
                  the provisions hereof. If the Company so elects or is
                  requested by the Selling Agent or such Other Indemnified
                  Party, the Company will assume the defense of such action or
                  proceeding, including the employment of counsel reasonably
                  satisfactory to the Selling Agent or such Other Indemnified
                  Party and the payment of the fees and expenses of such
                  counsel. In the event, however, the Selling Agent or such
                  Other Indemnified Party reasonably determines that having
                  common counsel would present such counsel with a conflict of
                  interest or if the defendants in or targets of any such action
                  or proceeding include both the Selling Agent or Other
                  Indemnified Party and the Company and the Selling Agent or
                  such Other Indemnified Party reasonably concludes that there
                  may be legal defenses available to it or Other Indemnified
                  Parties that are different from or in addition to those
                  available to the Company, or if the Company fails to assume
                  the defense of the action or proceeding or to employ counsel
                  reasonably satisfactory to the Selling Agent or such Other
                  Indemnified Party in a timely manner, then the Selling Agent
                  or such

                                       13

                  Other Indemnified Party may employ separate counsel to
                  represent or defend it in any such action or proceeding and
                  the Company will pay the reasonable and customary fees and
                  disbursements of such separate counsel (in addition to local
                  counsel, as needed) for the Selling Agent and such Other
                  Indemnified Parties in any jurisdiction in any single action
                  or proceeding. The Selling Agent and the Other Indemnified
                  Parties agree to utilize the same counsel unless it or they
                  reasonably conclude that the use of the same counsel would
                  create a disadvantage for the Selling Agent or the Other
                  Indemnified Parties. In any action or proceeding the defense
                  of which the Company assumes, the Selling Agent and the Other
                  Indemnified Party will have the right to participate in such
                  litigation and to retain its own counsel at, except in
                  accordance with the immediately preceding sentence, the
                  Selling Agent's or such Other Indemnified Parties' own
                  expense. The Company will be liable for any settlement of any
                  claim against the Selling Agent made with the Company's
                  written consent, which consent will not be unreasonably
                  withheld.

         (c)      If, for any reason, the foregoing indemnification is
                  unavailable to the Selling Agent or any of the Other
                  Indemnified Parties or is insufficient to hold them harmless
                  in respect of any Losses or Expenses, then the Company will
                  contribute to the amount paid or payable by the Selling Agent
                  or any of the Other Indemnified Parties as a result of such
                  Losses and Expenses in such proportion as is appropriate to
                  reflect the relative benefits (or anticipated benefits) to the
                  Company and its stockholders on the one hand and the Selling
                  Agent and the Other Indemnified Parties on the other hand from
                  the transactions contemplated hereby, or if such allocation is
                  not permitted by applicable law, then in such proportion as is
                  appropriate to reflect not only the relative benefits received
                  by the Company and its stockholders on the one hand and the
                  Selling Agent and the Other Indemnified Parties on the other
                  hand, but also the relative fault of the Company, its
                  directors, officers, employees, agents and advisers (other
                  than the Selling Agent) on the one hand and the Selling Agent
                  and the Other Indemnified Parties on the other hand, as well
                  as any other relevant equitable considerations. The relative
                  benefits received (or anticipated to be received) by the
                  Company and its stockholders on the one hand and by the
                  Selling Agent and the Other Indemnified Parties on the other
                  hand will be deemed to be in the same proportion as the
                  aggregate public offering price of the Shares in the Offering
                  bears to the total fees paid to the Selling Agent hereunder.
                  The relative fault of any party or other person will be
                  determined by reference to such party's or person's knowledge,
                  access to information and opportunity to prevent or correct
                  any misstatement, omission, misconduct or breach of duty. In
                  no event will the amount required to be contributed by the
                  Selling Agent and the Other Indemnified Parties hereunder
                  exceed the total amount of fees paid to the Selling Agent
                  hereunder. The Company and the Selling Agent agree that it
                  would not be just and equitable if contribution were
                  determined by pro rata allocation or by any other method of
                  allocation which does not take account of the equitable
                  considerations referred to above.


                                       14

         (d)      The reimbursement, indemnity and contribution obligations of
                  the Company hereunder will (i) be in addition to any liability
                  which the Company may otherwise have, (ii) survive the
                  completion or termination of the Selling Agent's engagement
                  hereunder and (iii) shall be binding upon any successors and
                  assigns of the Company.

         (e)      In the event that any litigation, investigation or proceeding
                  relating to the transaction contemplated hereunder is
                  commenced or threatened against the Company, the Company will
                  not settle any such pending or threatened litigation,
                  investigation or proceeding unless (i) the Selling Agent, by
                  name, and the Other Indemnified Parties, by description, are
                  included in any release or settlement agreement, whether or
                  not the Selling Agent and the Other Indemnified Parties are
                  named as defendants in such litigation or proceeding, (ii) the
                  Selling Agent and the Other Indemnified Parties are
                  unconditionally released from all claims and liabilities
                  asserted or which could have been asserted in such litigation,
                  investigation or proceeding and (iii) there is no statement in
                  any such release or settlement agreement as to an admission of
                  fault, culpability or failure to act by or on behalf of the
                  Selling Agent or the Other Indemnified Parties.

8.       Termination.

         The Selling Agent's engagement hereunder may be terminated by either
the Company or the Selling Agent at any time, with or without cause, upon
written notice to the other party; provided, however, that (a) no such
termination will affect the Selling Agent's right to expense reimbursement under
Section 6, the payment of any accrued and unpaid fees pursuant to Section 5 or
the indemnification contemplated by Section 7 and (b) if the Company consummates
an offering of (i) securities directly or indirectly from the Company within
twelve months following such termination with any party which the Selling Agent
has identified or in respect of which the Selling Agent has rendered advice
prior to such termination or (ii) shares of Common Stock directly from the
Company pursuant to the Registration Statement within twelve months following
such termination with any party with which the Company has directly or
indirectly held discussions or furnished information regarding the Company prior
to such termination, then the Selling Agent will be entitled to a
finders/financial advisory fee to be agreed upon by the parties.

9.       Notices.

         For the purposes of giving notices in connection with this Agreement,
notices may be given by personal delivery, facsimile or overnight courier,
effective upon receipt, to the following addresses and facsimiles for each
party:

         To the Company:            Cepheid
                                    904 Caribbean Drive
                                    Sunnyvale, California 94089
                                    Facsimile No.: (408) 541-4191
                                    Attention:  Chief Executive Officer


                                       15

         With a copy to             Fenwick & West LLP
                                    275 Battery Street
                                    San Francisco, California 94306
                                    Facsimile No.:  (415) 281-1350
                                    Attention:  Douglas N. Cogen

         To the Selling Agent:      William Blair & Company, L.L.C.
                                    222 West Adams Street
                                    Chicago, Illinois 60606
                                    Facsimile No.:  (312) 368-9418
                                    Attention:  Legal Department

         With a copy to:            Katten Muchin Zavis Rosenman
                                    525 West Monroe Street
                                    Suite 1600
                                    Chicago, Illinois 60661
                                    Facsimile No.:  (312) 902-1061
                                    Attention:  Adam R. Klein

10.      Miscellaneous.

         (a)      Entire Agreement. This Agreement, the Engagement Letter and
                  the Indemnification Letter Agreement dated June 24, 2002
                  between the parties hereto (the "Indemnification Agreement")
                  constitute the entire understanding between the parties
                  regarding the subject matter of this Agreement, and may be
                  altered or changed only by written agreement of the parties.
                  To the extent any of the provisions herein conflict with the
                  provisions in the Engagement Letter or the Indemnification
                  Agreement, the provisions herein shall govern.

         (b)      Assignability. Neither the Company nor the Selling Agent may
                  assign its rights or obligations under this Agreement without
                  the prior written approval of the other party. This Agreement
                  will be binding upon all permitted successors, assigns, or
                  transferees of the parties.

         (c)      Representations and Indemnities to Survive Delivery. The
                  respective indemnities, agreements, representations,
                  warranties and other statements of the Company and its
                  officers, 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 the Selling Agent or any
                  of its partners, principals, members, offices or directors or
                  any controlling persons be, and will survive delivery of and
                  payment for the Shares sold hereunder.

         (d)      Construction. This Agreement shall be governed by and
                  construed in accordance with the laws of the State of
                  Illinois, without giving affect to the principals of conflicts
                  of laws. The Company irrevocably submits to the jurisdiction
                  of any court of the State of Illinois or the United States
                  District Court of the Northern District of the State of
                  Illinois for the purpose of any suit, action or other
                  proceeding arising out of this Agreement or the transactions
                  contemplated hereby,

                                       16

                  which is brought by or against the Company. Each of the
                  Company (and, to the extent permitted by law, on behalf of the
                  Company's equity holders and creditors) and the Selling Agent
                  hereby knowingly, voluntarily and irrevocably waives any right
                  it may have to a trial by jury in respect of any claim based
                  upon, arising out of or in connection with the indemnification
                  provisions in Section 7.

         (e)      Counterparts. This Agreement may be executed in one or more
                  counterparts, and if so executed shall together constitute a
                  single instrument.

         (f)      Headings. The headings and captions of this Agreement are
                  inserted for convenience of reference only and shall not be
                  deemed a part hereof or used in the construction or
                  interpretation of this Agreement.


                                       17

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

                                             CEPHEID

                                             By:       /s/ John L. Bishop
                                             Name:     John L. Bishop
                                             Title:    Chief Executive Officer



                                             WILLIAM BLAIR & COMPANY, L.L.C.
                                             By:       /s/ Kelly J. Martin
                                             Name:     Kelly J. Martin
                                             Title:    Principal


                                       18