THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT
           --------------------------------------------------------

          THIS THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT
("Amendment") is entered into among AMERISOURCE CORPORATION, a Delaware
corporation ("Borrower"), GENERAL ELECTRIC CAPITAL CORPORATION, a corporation
organized under the banking laws of the State of New York ("GE Capital"), Co-
Agents (as defined in the Credit Agreement, as defined below), and each of the
other lenders thereunder (collectively, the "Lenders" and each, a "Lender"), GE
Capital and BANKERS TRUST COMPANY, a corporation organized under the banking
laws of the State of New York ("BTCo"), as managing agents, BTCo, as the issuing
lender, and GE Capital, as the administrative agent for Lenders (in such
capacity, "Agent"), as of November 27, 1995, with reference to the following
facts:

                                    RECITALS
                                    --------

     A.   Borrower, GE Capital, individually and in its capacities as a managing
agent and Agent, BTCo, individually and in its capacities as a managing agent
and the issuing lender, Co-Agents, and each of the other Lenders, have entered
into that certain Amended and Restated Credit Agreement dated as of December 13,
1994, as amended by that certain First Amendment to Credit Agreement dated as of
February 10, 1995 and that certain Second Amendment to Credit Agreement dated as
of September 30, 1995 (as amended, the "Credit Agreement"), pursuant to which
Lenders agreed to make certain financial accommodations to or for the benefit of
Borrower upon the terms and conditions contained therein.  Unless otherwise
defined in this Amendment, (i) capitalized terms used herein shall have the
meanings given to them in the Credit Agreement, and (ii) references to sections
and subsections shall refer to sections or subsections of the Credit Agreement.

     B.   Borrower has requested that Lenders make certain amendments to, and
consent to certain matters under, the Credit Agreement, and Lenders are willing
to do so subject to the terms and conditions set forth in this Amendment.

          NOW, THEREFORE, in consideration of the continued performance by
Borrower of its promises and obligations under the Credit Agreement and the
other Loan Documents, and for other good and valuable consideration, the receipt
and sufficiency of which are hereby acknowledged, Borrower and Lenders hereby
agree as follows:


                                 A G R E E M E N T
                                 - - - - - - - - -

     1.  INCORPORATION OF CREDIT AGREEMENT AND OTHER LOAN DOCUMENTS.
         ----------------------------------------------------------  
Except as expressly modified under this Amendment, all of the terms and
conditions set forth in the Credit Agreement and the other Loan Documents are
incorporated herein by this reference, and the obligations of Borrower under the
Credit 

                                       1

 
Agreement and the other Loan Documents are hereby acknowledged, confirmed
and ratified by Borrower.

     2.   AMENDMENTS TO CREDIT AGREEMENT.
          ------------------------------ 

          2.1 Section 5.1(c) of the Credit Agreement is hereby amended to
delete the first parenthetical, and the following is substituted therefor:

          (other than, at any time after there has been a public offering of the
          Stock of Borrower or Parent, for any Fiscal Quarter ending September
          30)

          2.2  Section 5.1(c) of the Credit Agreement is hereby amended to
delete the following language:
          
          and (iv) a statement reconciling Borrower's internally-prepared
          monthly financial statements with the quarterly reports filed by
          Borrower with the Securities and Exchange Commission.

          2.3  Section 5.1(d) of the Credit Agreement is hereby deleted in its
entirety, and the following is substituted therefor:
         
               (d) Within 90 days after the close of each Fiscal Year, a copy of
          the annual audited financial statements of Parent and its
          Subsidiaries, on a consolidated basis, consisting of balance sheet and
          statements of income, retained earnings and cash flow, setting forth
          in comparative form the figures for the previous Fiscal Year, which
          financial statements shall be prepared in accordance with GAAP,
          certified without qualification by the Auditors and accompanied by (i)
          a statement in reasonable detail showing the calculations used in
          determining Borrower's compliance with the Financial Covenants and
          calculations of the Interest Coverage Ratio and Total Debt to EBITDA
          Ratio, (ii) a report from the Auditors to the effect that in
          connection with their audit examination, nothing has come to their
          attention to cause them to believe that a Default or Event of Default
          had occurred, (iii) a certification of the chief executive officer,
          chief accounting officer, or chief financial officer of each of Parent
          and Borrower that, to his or her knowledge, after due inquiry, all 
          such financial statements are complete and correct and present fairly
          in accordance with GAAP the financial position, the results of 
          operations and the changes in financial position of Parent and its
          subsidiaries, on a consolidated basis, as at the end of such Fiscal
          Year and for the period then ended and specifying wheither, to his or
          her knowledge, after due

                                       2

 
          inquiry, there was any Default or Event of Default in existence as of
          such time, and (iv) if the generally accepted accounting principles in
          the United States of America as adopted by Parent or Borrower at any
          time differ from the generally accepted accounting principles in the
          United States of America as adopted by Borrower on September 30, 1994,
          then a written statement from the chief executive officer, chief
          accounting officer, or chief financial officer of each of Parent and
          Borrower setting forth the changes, if any, that would have resulted
          to the calculations described in clause (i) of this SECTION 5.1(D) if
          the financial statements described in this SECTION 5.1(D) had been
          prepared without giving effect to such accounting change.
               
          2.4  Section 5.1(e) of the Credit Agreement is hereby deleted in its
entirety, and the following is substituted therefor:

          (e) Within 90 days after the end of any Fiscal Quarter ending
          September 30 (at any time after there has been a public offering of
          the Stock of Borrower or Parent), (i) a copy of the unaudited balance
          sheets of Borrower, on a Consolidated and consolidating basis, and the
          Consolidated Borrower Group as of the end of such Fiscal Quarter and
          the related statements of income and cash flow for such Fiscal Quarter
          and a management letter, each prepared in accordance with GAAP
          (subject to normal year end adjustments and the inclusion of
          footnotes), setting forth in comparative form in each case (A) the
          previously projected figures for such period and (B) the figures from
          the same period for the immediately prior Fiscal Year, accompanied by
          (I) a statement in reasonable detail showing (x) the calculations used
          in determining Borrower's compliance with the Financial Covenants and
          calculations of the Interest Coverage Ratio and Total Debt to EBITDA
          Ratio, and (y) the calculations used in determining the amounts added
          to the Dividend/Acquisition Basket, together with a summary of each
          transaction (including the Acquisition Purchase Price for such
          transaction), in which amounts from the Dividend/Acquisition Basket
          were utilized, and (II) the certification of the chief executive
          officer, chief accounting officer, or chief financial officer of
          Borrower that all such financial statements are, to his or her
          knowledge, after due inquiry, complete and correct and present fairly
          in accordance with GAAP (subject to normal year end adjustments and
          the inclusion of footnotes), the financial position and the results of
          operations of Borrower, on a Consolidated
          

                                       3

 
          and consolidating basis, and the Consolidated Borrower Group as at the
          end of such Fiscal Quarter and for the period then ended, and
          specifying whether, to his or her knowledge, after due inquiry, there
          was any Default or Event of Default in existence as of such time, and
          (ii) if the generally accepted accounting principles in the United
          States of America as adopted by Borrower at any time differ from the
          generally accepted accounting principles in the United States of
          America as adopted by Borrower on September 30, 1994, then a written
          statement from the chief executive officer, chief accounting officer,
          or chief financial officer of Borrower setting forth the changes, if
          any, that would have resulted to the calculations described in clause
          (i)(B)(I) of this SECTION 5.1(E) if the financial statements described
          in this SECTION 5.1(E) had been prepared without giving effect to such
          accounting change.

          2.5 Clause (a) of Section 7.14 of the Credit Agreement is hereby
deleted in its entirety, and the following is substituted therefor:

          (a) to pay dividends or make advances to Parent (i) to enable Parent
          to pay current cash interest to the holders of the Subordinated Parent
          Notes, (ii) to allow Parent to redeem Subordinated Parent Notes or
          repurchase Subordinated Parent Notes on the open market, and (iii) to
          enable Parent to make distributions to its Stockholders; provided,
                                                                   -------- 
          that (x) except as described in clause (y) below, the Interest
          Coverage Ratio (adjusted to include payment of the proposed dividend
          as if that dividend were an interest expense), exceeds 2.5 to 1.0 for
          the Testing Period, (y) with respect to those dividends or advances
          described in clause (i) above, the Interest Coverage Ratio (adjusted
          to include payment of the proposed dividend as if that dividend were
          an interest expense), exceeds 2.5 to 1.0 for the Rolling Period (I)
          ending on March 31 of any Fiscal Year, if such payment is to be made
          on July 15 of such Fiscal Year, and (II) ending on September 30 of any
          Fiscal Year, if such payment is to be made on January 15 of the
          immediately succeeding Fiscal Year, and (z) the amount of such
          dividends that is permitted shall be limited to the then available
          Dividend/Acquisition Basket; and provided further, that
                                       --- -------- -------      
          notwithstanding the foregoing, (I) Borrower shall not, in any event,
          permit Parent to use such dividends to make distributions to Parent's
          Stockholders unless a Qualified Borrower Public Offering or Qualified
          Parent Public Offering has been completed, and (II) the aggregate
          amount of the dividends to Parent's 

                                       4

 
          Stockholders shall not, in any event, exceed 20% of the available
          amount under the Dividend/Acquisition Basket;

          2.6  Section 7.20 of the Credit Agreement is hereby deleted in its
entirety, and the following is substituted therefor:

               7.20 Capital Expenditures.  The Consolidated Borrower Group shall
                    --------------------                                        
          not make aggregate Capital Expenditures in excess of the amounts set
          forth below for the Fiscal Year corresponding thereto:


                     Fiscal Year                   Amount
                     -----------                   ------
                                                
                     1996                          $16,000,000
                     1997                          $17,000,000
                     1998                          $19,000,000
                     1999                          $21,000,000


          provided, as a carry-forward, Capital Expenditures for any Fiscal Year
          --------                                                              
          may be increased by the lesser of (a) one-half of the amount listed
          above for the immediately preceding Fiscal Year, and (b) the amount
          not expended for such preceding Fiscal Year and without giving effect
          to any increase to the amount permitted during such preceding Fiscal
          Year pursuant to this Section; and provided further, that for purposes
                                         --- -------- -------                   
          of this proviso, Capital Expenditures shall not include the cost of
          repair or replacement of any fixed assets or improvements as a result
          of a casualty loss, to the extent paid or reimbursed from insurance or
          from any other Person.  The parties to this Agreement acknowledge
          that, during the Fiscal Year ending September 30, 1995, Borrower is
          entitled to a carry-forward of $3,300,000 relating to the Fiscal Year
          ending September 30, 1994 and that such amount is otherwise subject to
          the terms of this SECTION 7.20.

     3.   CONSENT.  Notwithstanding any contrary term or provision set forth in
          -------                                                              
the Credit Agreement or the other Loan Documents, Lenders hereby consent,
subject to the terms and conditions set forth below, to the following:

          (a) the change of the corporate name of Borrower's Subsidiary, Health
     Services Plus, Inc., to "AmeriSource Health Services Corporation"; and

          (b) Borrower's entering into a sale-leaseback with Gelco Corporation,
     a Minnesota corporation, doing business as GE Capital Fleet Services, on
     substantially the same terms as the Master Lease Agreement, a copy of which
     is attached hereto as Exhibit A.
                           --------- 

                                       5

 
As a result of this Amendment, the foregoing matters shall be permitted under
the Credit Agreement and the other Loan Documents and shall not be a breach or
default thereunder.

     4.   CONDITIONS OF EFFECTIVENESS.  This Amendment shall become effective
          ---------------------------                                        
upon satisfaction of each of the following conditions:

               (a) Agent shall have received copies of this Amendment that, when
     taken together, bear the signatures of Borrower and Requisite Lenders; and

               (b) Agent shall have received a copy of the accompanying
     Guarantor Consents executed by Parent, AmeriSource Health Services
     Corporation (formerly known as Health Services Plus, Inc.) and Health
     Services Capital Corporation.

     5.   ENTIRE AGREEMENT.  This Amendment, together with the Credit Agreement
          ----------------                                                     
and the other Loan Documents, is the entire agreement between the parties hereto
with respect to the subject matter hereof.  This Amendment supersedes all prior
and contemporaneous oral and written agreements and discussions with respect to
the subject matter hereof.  Except as otherwise expressly modified herein, the
Credit Agreement and the other Loan Documents shall remain in full force and
effect.

     6.   REPRESENTATIONS AND WARRANTIES.  Borrower hereby represents and
          ------------------------------                                 
warrants that the representations and warranties contained in the Credit
Agreement were true and correct in all material respects when made and, except
to the extent (a) that a particular representation or warranty by its terms
expressly applies only to an earlier date, or (b) Borrower has previously
advised Agent in writing as contemplated under the Credit Agreement, are true
and correct in all material respects as of the date hereof.

     7.   MISCELLANEOUS.
          ------------- 

          7.1  Counterparts.  This Amendment may be executed in identical
               ------------                                              
counterpart copies, each of which shall be an original, but all of which shall
constitute one and the same agreement.  Delivery of an executed counterpart of a
signature page to this Amendment by facsimile transmission shall be effective as
delivery of a manually executed counterpart of this Amendment.  Any Lender
delivering this Amendment by facsimile shall send the original manually executed
counterpart of this Amendment to Agent's counsel promptly after such facsimile
transmission.

          7.2  Headings.  Section headings used herein are for convenience of
               --------                                                      
reference only, are not part of this Amendment,

                                       6

 
and are not to be taken into consideration in interpreting this Amendment.

          7.3  Recitals.  The recitals set forth at the beginning of this
               --------                                                  
Amendment are true and correct, and such recitals are incorporated into and are
a part of this Amendment.

          7.4  Governing Law.  This Amendment shall be governed by, and
               -------------                                           
construed and enforced in accordance with, the laws of the State of New York
applicable to contracts made and performed in such state, without regard to the
principles thereof regarding conflict of laws.

          7.5  No Novation.  Except as specifically set forth in section 2 of
               -----------                                                   
this Amendment, the execution, delivery and effectiveness of this Amendment
shall not (a) limit, impair, constitute a waiver by, or otherwise affect any
right, power or remedy of, Agent or any Lender under the Credit Agreement or any
other Loan Document, (b) constitute a waiver of any provision in the Credit
Agreement or in any of the other Loan Documents, or (c) alter, modify, amend or
in any way affect any of the terms, conditions, obligations, covenants or
agreements contained in the Credit Agreement, all of which are ratified and
affirmed in all respects and shall continue in full force and effect.

          7.6  Conflict of Terms.  In the event of any inconsistency between the
               -----------------                                                
provisions of this Amendment and any provision of the Credit Agreement, the
terms and provisions of this Amendment shall govern and control.

          IN WITNESS WHEREOF, this Amendment has been duly executed as of the
date first written above.


                         BORROWER:
                         -------- 

                         AMERISOURCE CORPORATION,
                         a Delaware corporation


                         By /s/ Kurt J. Hilzinger
                            -----------------------------

                         Name   Kurt J. Hilzinger
                              ---------------------------

                         Title  Vice President, Treasurer
                              ---------------------------

                                       7

 
                         LENDERS:
                         ------- 

                         GENERAL ELECTRIC CAPITAL CORPORATION,
                         as Agent, a Managing Agent and a Lender


                         By /s/ Charles D. Chiodo
                            ---------------------------
                                Charles D. Chiodo
                                Duly Authorized Signatory


                         BANKERS TRUST COMPANY, as a Managing Agent, Issuing
                         Lender and a Lender


                         By /s/ Frederic W. Thomas Jr
                            ---------------------------

                         Name   Frederic W. Thomas Jr
                              -------------------------

                         Title  Vice President
                               ------------------------


                         BANKAMERICA BUSINESS CREDIT, INC., as a Co-Agent and a
                         Lender


                         By /s/ George Markowsky
                            ---------------------------

                         Name   George Markowsky
                              -------------------------

                         Title  Vice President
                               ------------------------


                         HELLER FINANCIAL, INC., as a Co-Agent
                         and as a Lender


                         By /s/ John Cappenella
                            ---------------------------

                         Name   John Cappenella
                              -------------------------

                         Title  Vice President
                               ------------------------

                                       8

 
                         BANK OF NEW YORK COMMERCIAL CORPORATION,
                         as a Lender


                         By /s/ Anthony Viola
                            -----------------------------

                         Name   Anthony Viola
                              ---------------------------
                         Title  Vice President
                               --------------------------


                         BANK OF MONTREAL, as a Lender
                      
      
                         By /s/ Irene M. Geller
                            -----------------------------

                         Name   Irene M. Geller
                              ---------------------------

                         Title  Director
                               --------------------------


                         BOT FINANCIAL CORPORATION, as a Lender


                         By /s/ Willian R. York, Jr.
                            -----------------------------

                         Name   Willian R. York, Jr.
                              ---------------------------

                         Title  Senior Vice President
                               --------------------------


                         THE CIT GROUP/BUSINESS CREDIT, INC.,
                         as a Lender


                         By /s/ Cyril A. Prince
                            -----------------------------

                         Name   Cyril A. Prince
                              ---------------------------

                         Title  Vice President
                               --------------------------


                         CORESTATES BANK, N.A., as a Lender


                         By /s/ Sherri A. Williams
                            -----------------------------

                         Name   Sherri A. Williams
                              ---------------------------

                         Title  Assistant Vice President
                               --------------------------

                                       9

 
                         THE FIRST NATIONAL BANK OF BOSTON,
                         as a Lender


                         By /s/Willian C. Purinion
                            ---------------------------

                         Name Willian C. Purinion
                              -------------------------

                         Title Vice President
                               ------------------------


                         GIROCREDIT BANK AKTIENGESELLSCHAFT
                         DER SPARKASSEN, GRAND CAYMAN ISLAND
                         BRANCH, as a Lender


                         By 
                            ___________________________

                         Name
                              _________________________

                         Title
                               ________________________

                         MERIDIAN BANK, as a Lender


                         By /s/Patrick B. Trainor
                            ---------------------------

                         Name Patrick B. Trainor
                              -------------------------

                         Title Assistant Vice President
                               ------------------------
                         
                         LASALLE NATIONAL BANK, as a Lender


                         By /s/Christopher G. Clifford
                            ---------------------------

                         Name Christopher G. Clifford
                              -------------------------

                         Title Senior Vice President
                               ------------------------


                                       10

 
                         NATIONSBANK OF GEORGIA, N.A.,
                         as a Lender


                         By 
                            ___________________________

                         Name 
                              _________________________

                         Title
                               ________________________


                         SANWA BUSINESS CREDIT CORPORATION,
                         as a Lender


                         By /s/Peter L. Skavia
                            ---------------------------

                         Name Peter L. Skavia
                              -------------------------

                         Title Vice President
                               ------------------------


                         SHAWMUT CAPITAL CORPORATION,
                         as a Lender


                         By 
                            ___________________________

                         Name
                              _________________________

                         Title
                               ________________________

                                       11