EXHIBIT  10.34 

         PORTIONS OF THIS DOCUMENT HAVE BEEN OMITTED (DESIGNATED BY AN
   ASTERIX (*) AND WHITE SPACE) AND FILED SEPARATELY WITH THE SECURITIES AND
   EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT DATED
                       JANUARY 31, 1996; FILE NO. 0-15609


                               THIRD AMENDMENT TO
                        DEVELOPMENT AND LICENSE AGREEMENT

Effective as of December 1, 1994,  Agouron  Pharmaceuticals,  Inc., a California
corporation  ("Agouron") and Japan Tobacco Inc., a Japanese  corporation ("JT"),
for good and valuable consideration, agree as follows:

(Terms containing an initial capitalized letter,  except as explicitly otherwise
indicated,  shall  have the  meanings  stated  in the  Development  and  License
Agreement, as defined below).

                                   BACKGROUND

Agouron and JT entered into a Development  and License  Agreement dated December
1, 1994 and the First and  Second  Amendments  to the  Development  and  License
Agreement.  The Development and License  Agreement,  as amended,  is hereinafter
referred to as the "D&L Agreement."

The parties  wish to amend and  restate  certain of the  attachments  to the D&L
Agreement.

                                    AMENDMENT

1.       Agouron  and JT  hereby  agree to amend  and  restate  the  below-noted
         Attachments  to the D&L  Agreement  to read  in full as  stated  in the
         correspondingly-numbered Attachments to this Third Amendment:

                Attachment 2        Trademark License Agreement
                Attachment 3        Product Manufacturing Specifications
                Attachment 4        Royalty Methodology and Accounting Terms/
                                    Definitions
                Attachment 6        Premarketing Expenses and Reimbursement 
                                    Procedures

          2.      Except as modified by the terms  contained  herein,  the 
          provisions of the D&L Agreement shall remain in full force and effect.

AGOURON PHARMACEUTICALS, INC.             JAPAN TOBACCO INC.

By:      /s/ Gary E. Friedman             By:      /s/ Masakazu Kakei
         --------------------------                ----------------------------
Name:    Gary E. Friedman                 Name:    Masakazu Kakei
         --------------------------                ----------------------------
Title:   Corporate VP & General           Title:   Executive Director 
         Counsel                                   Pharmaceuticals
         --------------------------                ----------------------------
Date:    July 28, 1997                    Date:    July 9, 1997
         --------------------------                ----------------------------


<PAGE>

                                  ATTACHMENT 2
                           TRADEMARK LICENSE AGREEMENT


This  Trademark  License,  effective as of December 1, 1994, is between  Agouron
Pharmaceuticals,  Inc., a California corporation ("Agouron"),  and Japan Tobacco
Inc., a Japanese  corporation ("JT").  Agouron and JT are sometimes  hereinafter
referred to as a party (collectively "parties") to this Trademark License.

(Terms containing an initial capitalized letter,  except as explicitly otherwise
indicated,  shall  have the  meanings  stated in the D&L  Agreement,  as defined
below).

                                   BACKGROUND

Agouron and JT entered into a Development  and License  Agreement dated December
1, 1994,  and the First and Second  Amendments  to the  Development  and License
Agreement.  The  Development  and  License  Agreement,  as now  or  subsequently
amended, is hereinafter referred to as the "D&L Agreement."

The parties  have  conducted  collaborative  development  and  commercialization
activities for the HIV protease  inhibitor  nelfinavir  mesylate pursuant to the
terms of the D&L Agreement.

The D&L Agreement provides that a form trademark license shall be agreed upon by
the parties and attached to the D&L Agreement as Attachment 2. The D&L Agreement
also contains the following provisions  concerning the ownership and utilization
of Trademarks:

         Section 1.34 "Trademark(s)" means any trademark selected and owned by a
         party and registered by such party, its Affiliate(s) and sublicensee(s)
         in the Territory for use in connection with the marketing of Products.

         Section 2.01      License Grants.

                            (k)     *












                                      A2-1
<PAGE>

                   Section 3.03     Trademarks.  *




















The  provisions  of Section  2.01(k) of the D&L  Agreement  were  amended by the
Second Amendment to the D&L Agreement to provide that each party *


                   as such terms are defined in the Letter of Intent  ("LOI")  
dated  January 17,  1997  between  Roche and Agouron and JT.

One or both of the parties is the owner(s) of the Viracept Trademark, in certain
countries of the Territory.

The parties  intend to use the  Viracept  Trademark,  including  its  associated
non-English translations  (hereinafter collectively referred to as the "Viracept
Trademark"), *
                                                in  their  respective  Exclusive
Territories.

                                      A2-2
<PAGE>

NOW THEREFORE, in accordance with the provisions of the D&L Agreement,  for good
and valuable consideration, the parties agree as follows:

                                TRADEMARK LICENSE

          1.      Under the provisions of the D&L Agreement, as more 
specifically set forth above, each party *



2.       The parties' rights in Trademark(s) are *


3.       Products  marketed using the Viracept  Trademark shall be manufactured
         strictly  in  accordance   with  applicable   governmental   statutes,
         regulations or directives.

4.       The  licensed  user of the  Viracept  Trademark  shall  comply with all
         applicable governmental statutes, regulations or directives.

5.       The licensed user of the Viracept  Trademark shall not use the Viracept
         Trademark  in a manner  which is  deceptive,  or which  would bring the
         Viracept  Trademark,  the Product or the other party,  into  disrepute.
         Each party shall use the Viracept  Trademark,  including its associated
         non-English translations, *


6.       Pursuant to the terms of the D&L Agreement, *


         Provided a party fulfills its obligations and responsibilities  related
         to  Trademark(s)  and subject to the terms of the D&L  Agreement,  such
         party shall *




7.       Administration  of this Trademark  license shall be undertaken,  in 
         accordance with the procedures  established by Section 4.01 of the D&L 
         Agreement, *


8.       Each party shall,  upon  learning  thereof,  promptly  notify the other
         party in writing of any  infringement  by a third party of the parties'
         rights in the  Viracept  Trademark,  or of any claim or suit by a third
         party that the use of the  Viracept  Trademark  infringes  or otherwise
         violates the rights of a third party. The parties shall *




                                      A2-3
<PAGE>






9.       Only  the  licenses  granted  pursuant  to the  express  terms  of this
         Trademark License and the D&L Agreement shall be of any legal force and
         effect. No license rights shall be created by implication or estoppel.

10.      This Trademark License shall terminate *


11.      Any  failure  by either  party to enforce  any right  which it may have
         hereunder in any instance  shall not be deemed to waive any right which
         it or the other party may have in any other  instance  with  respect to
         any provisions of this Trademark License, including the provision which
         such party has failed to enforce.

12.      In the event that any provision of this Trademark License is judicially
         determined  to be  unenforceable,  in whole or in part,  the  remaining
         provisions or portions thereof of this Trademark License shall be valid
         and  binding to the fullest  extent  possible,  and the  parties  shall
         endeavor to negotiate additional terms, as feasible, in a timely manner
         so as to fully  effectuate the original  intent of the parties,  to the
         extent possible.  Ambiguities,  if any, in this Trademark License shall
         not be construed against any party,  irrespective of which party may be
         deemed to have authored the ambiguous provision.

13.      This  Trademark  License  and the D&L  Agreement  constitute  the  full
         agreement  of the parties  with  respect to the subject  matter of this
         Trademark License,  and incorporate any prior discussions  between them
         with respect to such subject matter.  This Trademark  License shall not
         be amended, supplemented or otherwise modified, except by an instrument
         in writing signed by a duly authorized officer of each party.

14.      If there is a conflict between the terms of this Trademark  License and
         the D&L Agreement, the terms of the D&L Agreement shall control.

15.      This  Trademark  License  shall be  construed,  and the  rights  of the
         parties shall be determined, in accordance with *


16.      Any notice  required  or  permitted  to be given  under this  Trademark
         License shall be in writing and shall be given in person,  delivered by
         recognized  overnight  delivery  service,  sent by mail  (certified  or
         registered, or air mail for addresses outside of the continental U.S.),
         or by telefax  (or other  similar  means of  electronic  communication)
         whose receipt is confirmed by confirming telefax, and addressed, in the
         case of Agouron,  to the President  and, in the case of JT, to the Vice
         President, Pharmaceutical Division at the respective 

                                      A2-4
<PAGE>

         addresses  shown at the  beginning  of the D&L  Agreement or such other
         person  and/or  address  as may have been  furnished  in writing to the
         notifying  party in accordance  with the provisions of this  paragraph.
         Except  as  otherwise  provided  herein,  any  notice  shall be  deemed
         delivered upon the earlier of (i) actual receipt, (ii) two (2) business
         days after delivery to such overnight  express service,  (iii) five (5)
         business days after deposit in the mail, or (iv) the date of receipt of
         the confirming telefax.

17.      This  Trademark  License  shall  be  binding  upon  all  successors  in
         interest,  assigns,  trustees  and other legal  representatives  of the
         parties.


IN WITNESS WHEREOF,  the parties hereto have executed this Trademark License, in
duplicate  originals,  by their respective officers thereunto duly authorized as
of the day and year hereinabove written.

AGOURON PHARMACEUTICALS, INC.           JAPAN TOBACCO INC.



By:      /s/ Gary E. Friedman           By:      /s/ Masakazu Kakei

Name:    Gary E. Friedman, Esq.         Name:    Masakazu Kakei

Title:   Vice President and             Title:   Executive Director
         General Counsel                         Pharmaceuticals

                                      A2-5
<PAGE>


                                  ATTACHMENT 3
                      PRODUCT MANUFACTURING SPECIFICATIONS





 THE TERMS OF THE PRODUCT MANUFACTURING SPECIFICATIONS ARE THOSE CONTAINED IN 
         THE APPLICABLE REGISTRATION FILING FOR THE PRODUCT, AS AMENDED

                                      A3-1
<PAGE>
                                                       
                                  ATTACHMENT 4

                    ROYALTY METHODOLOGY AND ACCOUNTING TERMS

*



                                                         *

*


1.       *

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                  *
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                  *                                                          *
                                      A4-1
<PAGE>

2.       *

*






3.       *

*





4.       *

*


         (a)      *




         (b)      *



         (c)      *



 4.1     *

*








                                      A4-2
<PAGE>

4.2      *

*



4.3      *

*










4.4      *

*













5.       *

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*




                                      A4-3
<PAGE>











6.       *

*






*















7.       *

*








                                      A4-4
<PAGE>



8.       *

*









9.       *

*





9.1      *

*



9.2      *

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*












                                      A4-5
<PAGE>


                                        *

*

                                        *

*














<PAGE>

                                        *

*







*

















*







*


         (i)      *


         (ii)     *


         (iii)    *


                                    A4-SA-1
<PAGE>

         (iv)     *


*


*

*












*

*

*












*






                                    A4-SA-2
<PAGE>









*

                                    A4-SA-3
<PAGE>


                                  ATTACHMENT 6

               PREMARKETING EXPENSES AND REIMBURSEMENT PROCEDURES



 THE DETAILS RELATING TO THE DEFINITION AND TREATMENT OF PREMARKETING EXPENSES *

                                      A6-1