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                                                                    EXHIBIT 10.8

                                    AMENDMENT
                         Dated as of September 28, 1998
                                       to
                         RECEIVABLES PURCHASE AGREEMENT
                           Dated as of August 28, 1997


                  THIS AMENDMENT (this "Amendment") dated as of September 28,
1998 is entered into by and between NMC FUNDING CORPORATION, a Delaware
corporation, as Purchaser (the "Purchaser") and NATIONAL MEDICAL CARE, INC., a
Delaware corporation, as Seller (the "Seller").

                              PRELIMINARY STATEMENT

                  A.       The Purchaser and the Seller are parties to that
certain Receivables Purchase Agreement dated as of August 28, 1997 (as amended
or otherwise modified prior to the date hereof, the "RPA"). Capitalized terms
used herein and not otherwise defined shall have the meanings ascribed to them
in the RPA.

                  B.       The Purchaser and the Seller have agreed to amend the
RPA on the terms and conditions hereinafter set forth.

                  NOW, THEREFORE, in consideration of the premises set forth
above, and other good and valuable consideration the receipt and sufficiency of
which is hereby acknowledged, the parties hereto agree as follows:

                  SECTION  1. Amendments to the RPA. Subject to the satisfaction
of the conditions precedent set forth in Section 2 below, the RPA is amended as
follows:

                  1.1.     The following new definitions are added to Section
1.1 of the RPA in appropriate alphabetical order:

         "Receivable Systems" has the meaning specified in Section 3.1(z).

         "Year 2000 Compliant" has the meaning specified in Section 3.1(z).

                  1.2.     Section 3.1 of the RPA is amended to add, immediately
after paragraph (y), the following new paragraph (z):



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         "(z) Year 2000 Compliance. The Seller has (i) initiated a review and
assessment of all areas within its and each of its Subsidiaries' business and
operations (including those affected by suppliers, vendors and customers) that
could be adversely affected by the 'Year 2000 Problem' (that is, the risk that
computer applications used by the Seller or any of its Subsidiaries (or
suppliers, vendors and customers) may be unable to recognize and perform
properly date-sensitive functions involving certain dates prior to and any date
after December 31, 1999), (ii) initiated the development of a plan and timeline
for addressing the Year 2000 Problem on a timely basis, and (iii) to date,
implemented that plan in accordance with that timetable. The Seller believes
that all computer applications (including those of its suppliers, vendors and
customers) that are material to its or any of its Subsidiaries' business and
operations are reasonably expected on a timely basis to be able to perform
properly date-sensitive functions for all dates before and after January 1, 2000
(that is, be 'Year 2000 Compliant'), except to the extent that a failure to do
so could not reasonably be expected (a) to have a Material Adverse Effect on the
Seller or on the transaction documented under this Agreement, or (b) to result
in a Termination Event.

         The Seller (i) has initiated a review and assessment of all computer
applications (including, but not limited to those of the Seller, any
Transferring Affiliate and any of their respective suppliers, vendors, customers
or third party servicers), which are related to or involved in the origination,
collection, management or servicing of the Receivables (the 'Receivable
Systems') and (ii) believes that such Receivable Systems are Year 2000 Compliant
or will be Year 2000 Compliant on or before April 1, 1999 and thereafter.

         The Seller believes that the costs of all assessment, remediation,
testing and integration related to the Seller's plan for becoming Year 2000
Compliant will not have a material adverse effect on the financial condition or
operations of the Seller."

                  1.3.     Section 5.1 of the RPA is amended to add, immediately
following paragraph (m), the following new paragraphs (n) and (o):

         "(n) Year 2000 Compliance: Reporting. The Seller will promptly notify
the Agent in the event the Seller discovers or determines that any computer
application (including those of its suppliers, vendors and customers) (i) that
is necessary for the origination, collection, management, or servicing of the
Receivables will not be Year 2000 Compliant on or before April 1, 1999 and
thereafter, or (ii) that is otherwise material to its or any of its
Subsidiaries' business and operations will not be Year 2000 Compliant on a
timely basis, except to the extent that, in the case of (ii) above, such failure
could not reasonably be expected (a) to have a Material Adverse Effect on the
Seller or on the transaction documented under this Agreement, or (b) to result
in a Termination Event.

         Further, the Seller will deliver simultaneously with any quarterly or
annual financial statements or reports to be delivered under the Agreement, a
certificate signed by an officer of the Seller that no material event, problems
or conditions have occurred 





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which in the opinion of management would (i) prevent or materially delay the
Seller's plan to become Year 2000 Compliant or (ii) cause Seller's or be likely
to cause the representations and warranties or covenants with respect to being
or becoming Year 2000 Compliant to no longer be true.

                  (o)      YEAR 2000 COMPLIANCE: IMPLEMENTATION: The Seller will
         cause (i) all computer applications (including those of its suppliers,
         vendors and customers) that are material to its or any of its
         Subsidiaries' business and operations to be Year 2000 Compliant on a
         timely basis, except to the extent that a failure to do so could not
         reasonably be expected (a) to have a Material Adverse Effect on the
         Seller or on the transaction documented under this Agreement, or (b) to
         result in a Termination Event; and (ii) all Receivable Systems to be
         Year 2000 Compliant at all times on and after April 1, 1999. The Seller
         will deliver a certificate to the Seller and the Agent, signed by the
         chief information officer of the Seller, certifying compliance with the
         foregoing covenant by no later than April 1, 1999."

         1.4.     Section 8.1 of the RPA is amended (a) to replace the period
appearing at the end of clause (xviii) with a semicolon followed by the word
"or" and (b) to add the following new clause (xix):

                  "(xix) any failure of the computer applications of the Seller
         or any Transferring Affiliate(including those of suppliers, vendors and
         customers of the Seller or any Transferring Affiliate and the
         Receivables Systems) to be Year 2000 Compliant at any time."

                  SECTION 2. CONDITIONS PRECEDENT. This Amendment shall become
effective and be deemed effective as of the date hereof upon the receipt by the
Agent of each of the following:

                  (i)      counterparts of this Amendment duly executed by the
Purchaser and the Seller; and

                  (ii)     a reaffirmation of the Parent Agreement,
substantially in the form of Exhibit A attached hereto, duly executed by each of
FMC and FMCH.

                  SECTION 3. COVENANTS, REPRESENTATIONS AND WARRANTIES OF THE
SELLER.

                  3.1      Upon the effectiveness of this Amendment, the Seller
hereby reaffirms (subject to the modifications to Exhibit F to the RPA set forth
in the Certificate of even date herewith executed by the Seller) all covenants,
representations and warranties made by it in the RPA and agrees that all such
covenants, representations and warranties shall be deemed to have been remade as
of the effective date of this Amendment.




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                  3.2      The Seller hereby represents and warrants that (i)
this Amendment constitutes the legal, valid and binding obligation of such
party, enforceable against it in accordance with its terms and (ii) upon the
effectiveness of this Amendment, no Seller Default or Potential Seller Default
shall exist under the RPA.

                  SECTION 4. REFERENCE TO AND EFFECT ON THE RPA.

                  4.1      Upon the effectiveness of this Amendment, each
reference in the RPA to "this Agreement," "hereunder," "hereof," "herein,"
"hereby" or words of like import shall mean and be a reference to the RPA as
amended hereby, and each reference to the RPA in any other document, instrument
and agreement executed and/or delivered in connection with the RPA shall mean
and be a reference to the RPA as amended hereby.

                  4.2      Except as specifically amended hereby, the RPA and
all other documents, instruments and agreements executed and/or delivered in
connection therewith shall remain in full force and effect and are hereby
ratified and confirmed.

                  4.3      The execution, delivery and effectiveness of this
Amendment shall not operate as a waiver of any right, power or remedy of the
Purchaser or any of its assignees under the RPA or any other document,
instrument, or agreement executed in connection therewith, nor constitute a
waiver of any provision contained therein.

                  SECTION 5. GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS (AS OPPOSED TO THE CONFLICT OF
LAW PROVISIONS) AND DECISIONS OF THE STATE OF NEW YORK.

                  SECTION  6. EXECUTION IN COUNTERPARTS. This 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 to be an original and all of which taken together shall constitute but
one and the same instrument.

                  SECTION 7. HEADINGS. Section headings in this Amendment are
included herein for convenience of reference only and shall not constitute a
part of this Amendment for any other purpose.





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


                                   NMC FUNDING CORPORATION,
                                   as Purchaser

                                   By: /s/ James V. Luther
                                       ------------------------------------ 
                                       James V. Luther
                                       Assistant Treasurer



                                   NATIONAL MEDICAL CARE, INC.,
                                   as Seller

                                   By: /s/ James V. Luther
                                       ------------------------------------ 
                                       James V. Luther
                                       Assistant Treasurer






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                                                                       EXHIBIT A

                    FORM OF REAFFIRMATION OF PARENT AGREEMENT

                        REAFFIRMATION OF PARENT AGREEMENT

                               September 28, 1998


NMC Funding Corporation
Two Ledgemont Center
95 Hayden Avenue
Lexington, Massachusetts 02173

NationsBank, N.A.,
         as Agent under the
         Transfer and Administration
         Agreement referred to below
NationsBank Corporate Center--10th Floor
Charlotte, North Carolina 28255


                  Each of the undersigned, FRESENIUS MEDICAL CARE AG and
FRESENIUS MEDICAL CARE HOLDINGS, INC. (i) acknowledges, and consents to, the
execution of that certain Amendment No. 3 dated as of September 28, 1998 (the
"TAA AMENDMENT") to the Transfer and Administration Agreement, dated as of
August 28, 1997, among Enterprise Funding Corporation, NMC Funding Corporation,
National Medical Care, Inc., the "Bank Investors" parties thereto and
NationsBank, N.A., as agent, (ii) acknowledges, and consents to, the execution
of that certain Amendment dated as of September 28, 1998 (the "RPA AMENDMENT")
to the Receivables Purchase Agreement, dated as of August 28, 1997, between NMC
Funding Corporation and National Medical Care, Inc., (iii) reaffirms all of its
obligations under that certain Parent Agreement dated as of August 28, 1997 made
by the undersigned and (iv) acknowledges and agrees that, after giving effect to
the TAA Amendment and the RPA Amendment, such Parent Agreement remains in full
force and effect and such Parent Agreement is hereby ratified and confirmed.




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                                        FRESENIUS MEDICAL CARE AG


                                        By: 
                                            ---------------------------------- 
                                            Title:


                                        FRESENIUS MEDICAL CARE
                                        HOLDINGS, INC.


                                        By: 
                                            ---------------------------------- 
                                            Title: