AMGEN INC.

                                  FOURTH AMENDMENT
                                 TO CREDIT AGREEMENT


                    This FOURTH AMENDMENT TO CREDIT AGREEMENT (this "Fourth
          Amendment") is dated as of June 24, 1994 and entered into by  and
          among Amgen  Inc., a  Delaware corporation  (the "Company"),  the
          subsidiaries of  the Company  signatory to  the Credit  Agreement
          defined below (together with the Company, the "Borrowers"), Swiss
          Bank Corporation, San Francisco  Branch, Citicorp USA, Inc.,  and
          each other lender whose name is set forth on the signature  pages
          of  the  Credit  Agreement   defined  below  (collectively,   the
          "Banks"), Swiss Bank Corporation, New York Branch as Issuing Bank
          (the "Issuing Bank"), and Swiss Bank Corporation, New York Branch
          and Citicorp  USA, Inc.  as Co-Agents  for  the Banks  (the  "Co-
          Agents").   This  Fourth  Amendment amends  that  certain  Credit
          Agreement dated  as  of November 15, 1991,  as  amended by  that
          certain First Amendment to Credit Agreement dated as of June  16,
          1992, that certain Second Amendment to Credit Agreement dated  as
          of November 6, 1992  and that certain  Third Amendment to  Credit
          Agreement dated as of June 25,  1993 (as so amended, the  "Credit
          Agreement") by and  among the Borrowers,  the Banks, the  Issuing
          Bank and the  Co-Agents.  Capitalized  terms used herein  without
          definition shall have the  same meanings herein  as set forth  in
          the Credit Agreement.


                                      RECITALS

                    WHEREAS, the Borrowers, the Banks, the Issuing Bank and
          the Co-Agents desire  to amend the  Credit Agreement as  follows:
          (i) to extend the  maturity dates of  the Tranche A-1  Commitment
          and the Tranche  A-2 Commitment,  (ii) to  reduce the  commitment
          fees payable with respect to the  Tranche A-1 Commitment and  the
          Tranche A-2 Commitment,  and (iii)  to reduce  the interest  rate
          spread applicable to Eurodollar Rate Advances.


                                      AGREEMENT

                    NOW, THEREFORE, in consideration  of the foregoing  and
          the mutual covenants and agreements set forth herein, the parties
          hereto agree as follows:


          Section 1.  AMENDMENTS TO SECTION 1 OF THE CREDIT AGREEMENT
          

                    (a) The table  entitled "Rate Spread  and LC Fees"  set
          forth in the definition  of "Applicable Percentage" contained  in
          Section 1.1  of the  Credit Agreement  is hereby  deleted in  its
          entirety and replaced with the following table:


                               Rate Spread and LC Fees

                                     Tier I        Tier II        Tier III

          Eurodollar Rate            .375%         .50%         .625%
          Spread

          LC Issuance Fee             .15%       .1875%        .1875%

          LC Reimbursement            .50%        .625%          .75%
            Fee


                    (b) The following definitions contained in Section  1.1
          of the Credit Agreement are hereby deleted in their entirety  and
          replaced with the following:

                    "'Tranche A-1 Maturity Date' means June 23, 1995."

                    "'Tranche A-2 Maturity Date' means June 23, 1995."

       Section 2.  AMENDMENTS TO SECTION 3 OF THE CREDIT AGREEMENT

                    (a) Subsection  3.2(a)(1) of  the Credit  Agreement  is
       hereby deleted in its entirety and replaced with the following:

                         "(1)  its  Pro  Rata  Share  of  the  Tranche  A-1
                    Commitment, commitment fees  equal to  12.5/100 of  one
                    percent (.125%)  per  annum  times  the  average  daily
                    Unused Portion of the Tranche A-1 Commitment during the
                    Fiscal Quarter then ending and".

                    (b) Subsection  3.2(a)(2) of  the Credit  Agreement  is
       hereby deleted in its entirety and replaced with the following:

                         "(2)  its  Pro  Rata  Share  of  the  Tranche  A-2
                    Commitment, commitment fees  equal to  12.5/100 of  one
                    percent (.125%)  per  annum  times  the  average  daily
                    Unused Portion of the Tranche A-2 Commitment during the
                    Fiscal Quarter then ending".

       Section 3.  REPRESENTATIONS AND WARRANTIES

                    In order to induce the Issuing Bank, the Co-Agents  and
       the Banks  to enter  into this  Fourth Amendment  and to  amend  the
       Credit Agreement  in  the  manner  provided  herein,  each  Borrower
       represents and warrants to each  Bank that the following  statements
       are true, correct and complete:
       


                    A.   Corporate Power and Authority.  Such Borrower  has
       all requisite corporate power and  authority to execute and  deliver
       this Fourth Amendment and to carry out the transactions contemplated
       by, and  perform  its obligations  under,  the Credit  Agreement  as
       amended by this Fourth Amendment (the "Amended Agreement").

                    B.   Authorization of  Agreements.   The execution  and
       delivery of this Fourth Amendment and the performance of the Amended
       Agreement have  been  duly  authorized by  all  necessary  corporate
       action by such Borrower.

                    C.   No  Conflict.     The   execution,  delivery   and
       performance of this  Fourth Amendment and  the Amended Agreement  by
       such Borrower  do  not  (i) require any  consent  or  approval  not
       heretofore obtained of any partner, director, stockholder,  security
       holder or creditor of such Borrower,  (ii) violate or conflict  with
       any provisions of  such Borrower's certificate  of incorporation  or
       bylaws, (iii) result in or require the creation or imposition of any
       Lien or Right  of Others upon  or with respect  to any Property  now
       owned or  leased  or  hereafter  acquired  by  such  Borrower,  (iv)
       violate, to the best knowledge of such Borrower, any Requirement  of
       Law applicable to such Borrower, or (v) result (or, with the  giving
       of notice or the passage of time or both, would result) in a  breach
       of or default  under, or  cause or  permit the  acceleration of  any
       obligation owed under, any indenture or loan or credit agreement  or
       any other Contractual Obligation to which  such Borrower is a  party
       or by  which  such Borrower  or  any of  its  Property is  bound  or
       affected.   Except as  set  forth in  Schedule  4.2 annexed  to  the
       Amended Agreement, such Borrower is not in violation of, or  default
       under, any  requirement of  Law or  Contractual Obligation,  or  any
       indenture, loan or credit agreement  described in Section 4.2(e)  of
       the Credit Agreement,  in any  respect that  constitutes a  Material
       Adverse Effect.

                    D.   Governmental Consents.  No authorization, consent,
       approval, order, license or permit from, or filing, registration  or
       qualification with, any Governmental Agency is required to authorize
       or  permit  under  applicable  Laws  the  execution,  delivery   and
       performance of the Amended Agreement by such Borrower.

                    E.   Binding Obligation.   This Fourth Amendment  will,
       when executed and delivered by such Borrower, constitute the  legal,
       valid and binding  obligation of such  Borrower enforceable  against
       such Borrower in  accordance with its  terms, except as  enforcement
       may be  limited by  Debtor Relief  Laws or  by equitable  principles
       relating to  the  granting  of specific  performance  and  equitable
       remedies as a matter of judicial discretion.

                    F.   Absence of Default.  No event has occurred and  is
       continuing that is a Default or an Event of Default.

       

       Section 4.  CONDITIONS TO EFFECTIVENESS

                    This Fourth Amendment shall become effective as of  the
       date when the Administrative  Agent, on behalf  of the Banks,  shall
       have  received  all  of  the   following,  in  form  and   substance
       satisfactory to  the  Administrative Agent  (the  "Fourth  Amendment
       Effective Date"):

                    (a)   Resolutions of  the Board  of Directors  of  each
       Borrower authorizing  and  approving  the  execution,  delivery  and
       performance of this Fourth Amendment, in  each case certified as  of
       the Fourth Amendment Effective Date by the secretary or an assistant
       secretary of such Borrower;

                    (b)  A  certificate of  the secretary  or an  assistant
       secretary of each  Borrower, which shall  certify as  of the  Fourth
       Amendment Effective Date the  names and offices  of the officers  of
       each Borrower authorized to sign this Fourth Amendment together with
       the true signatures of such officers; and

                    (c)  A counterpart hereof executed by a duly authorized
       officer of each party hereto and written or telephonic  notification
       of such execution and authorization of delivery thereof.

       Section 5.  MISCELLANEOUS

                    A.   Reference to and  Effect on  the Credit  Agreement
       and the Other Loan Documents.

                         (i)  On and after  the Fourth Amendment  Effective
               Date, each  reference  in  the  Credit  Agreement  to  "this
               Agreement", "hereunder", "hereof", "herein" or words of like
               import referring to the Credit Agreement, and each reference
               in the  other  Loan  Documents to  the  "Credit  Agreement",
               "thereunder", "thereof" or words of like import referring to
               the Credit Agreement shall  mean and be  a reference to  the
               Credit Agreement as amended by this Fourth Amendment.

                        (ii)  Except as specifically amended by this Fourth
               Amendment, the Credit Agreement and the other Loan Documents
               shall remain  in  full  force  and  effect  and  are  hereby
               ratified and confirmed.

                       (iii)  The execution,  delivery and  performance  of
               this  Fourth  Amendment  shall  not,  except  as   expressly
               provided herein, constitute a waiver of any provision of, or
               operate as a waiver of any right, power or remedy of the Co-
               Agents or any Bank under the Credit Agreement or any of  the
               other Loan Documents.

                         (iv)  Until the  Fourth Amendment Effective  Date,
               all terms  and  provisions  of the  Credit  Agreement  shall
               remain in effect, and  all fees shall  be calculated as  set
               forth therein.  On and after the Fourth Amendment  Effective
               Date, the commitment fees  shall be calculated as  described
               in this Fourth Amendment.
               

                    B.   Fees and Expenses.  The Company acknowledges  that
       all costs, fees and expenses as described in subsection 13.3 of  the
       Credit Agreement  incurred by  the Co-Agents  and its  counsel  with
       respect to this Fourth Amendment and the documents and  transactions
       contemplated hereby shall be for the account of Company.

                    C.   Execution in Counterparts.  This Fourth  Amendment
       may be  executed in  any number  of counterparts,  and by  different
       parties hereto  in  separate counterparts,  each  of which  when  so
       executed and delivered  shall be deemed  an original,  but all  such
       counterparts taken together  shall constitute but  one and the  same
       instrument.

                    D.   Applicable Law.   This Fourth  Amendment shall  be
       governed by, and shall be construed and enforced in accordance with,
       the Laws of the state of California applicable to contracts made and
       performed in such state.

                    E.   Fourth   Amendment    Effective   Date.        The
       Administrative Agent shall  give prompt notice  to each other  party
       hereto of the occurrence of the Fourth Amendment Effective Date.

       


                    IN WITNESS WHEREOF, the parties hereto have caused this
       Fourth Amendment to be executed as  of the date first above  written
       by their respective officers thereunto duly authorized.

                                        THE COMPANY:

                                        AMGEN INC.


                                        By: /s/ Thomas A. Hardy
                                        Name: Thomas A. Hardy
                                        Title: President

                                        BORROWING SUBSIDIARIES:

                                        AMGEN MANUFACTURING, INC.


                                        By: /s/Dennis Fenton
                                        Name: Dennis Fenton
                                        Title: Vice Presidnet

                                        THE CO-AGENTS:

                                        SWISS BANK CORPORATION,
                                        NEW YORK BRANCH


                                        By: /s/Jennifer L. Match
                                        Name: Jennifer L. Match
                                        Title: Associate Director


                                        By: /s/Sean M. Harrigan
                                        Name: Sean M. Harrigan
                                        Title: Executive Director

                                        CITICORP USA, INC.


                                        By: /s/Barbara A. Cohen
                                        Name: Barbara A. Cohen
                                        Title: Vice President
       



                                        THE ISSUING BANK:

                                        SWISS BANK CORPORATION,
                                        NEW YORK BRANCH


                                        By: /s/Jennifer L. Match
                                        Name: Jennifer L. Match
                                        Title: Associate Director


                                        By: /s/Sean M. Harrigan
                                        Name: Sean M. Harrigan
                                        Title: Executive Director

                                        THE BANKS:

                                        SWISS BANK CORPORATION,
                                        SAN FRANCISCO BRANCH


                                        By: /s/David L. Parrot
                                        Name: David L. Parrot
                                        Title: Associate Director


                                        By: /s/Colin T. Taylor
                                        Name: Colin T. Taylor
                                        Title: Director

                                        CITICORP USA, INC.


                                        By: /s/Barbara A. Cohen
                                        Name: Barbara A. Cohen
                                        Title: Vice President

                                        ABN AMRO BANK, N.V., Los
                                        Angeles Agency


                                        By: /s/Ellen M. Coleman
                                        Name: Ellen M. Coleman
                                        Title: Assistant Vice President
       


                                        BANK OF MONTREAL (formerly 
                                        Harris Trust and Savings Bank)


                                        By: /s/J. Donald Higgins
                                        Name: J. Donald Higgins
                                        Title: Managing Director

                                        THE SANWA BANK, LIMITED
                                        LOS ANGELES BRANCH


                                        By: /s/Gill S. Realon
                                        Name: Gill S. Realon
                                        Title: Vice President