Document:

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                                                                   EXHIBIT 10.11

                              SEPARATION AGREEMENT

This Agreement is entered into as of this 31st day of January, 2001 (the
"Effective Date") between Roger G. Stoll ("Mr. Stoll"), who currently resides at
2141 Oyster Harbor, Osterville, MA 02655, and Fresenius Medical Care Holdings,
Inc., d/b/a Fresenius Medical Care North America, with its principal offices
located at 95 Hayden Avenue, Lexington, Massachusetts 02420 ("FMC" or the
"Company").

                                   WITNESSETH:

     WHEREAS, on October 23, 1998, Mr. Stoll entered into an Employment
Agreement with National Medical Care, Inc. ("NMC"), a subsidiary of FMC (the
"Employment Agreement"), a copy of which is attached hereto as Exhibit A; and

     WHEREAS, Mr. Stoll and FMC now desire to enter into an agreement concerning
the separation of Mr. Stoll from FMC.

     NOW THEREFORE, in consideration of the mutual promises contained in this
Agreement, Mr. Stoll and FMC (the "Parties") agree as follows:

1)   SEPARATION: The Parties agree that Mr. Stoll shall continue to work for and
     be an employee of the Company through and including January 31, 2001 (the
     "Separation Date"), and that until he ceases to be an employee of the
     Company, Mr. Stoll shall continue to hold the position of Executive Vice
     President. FMC represents and Mr. Stoll agrees that the termination of Mr.
     Stoll's employment is not a termination for cause, as set forth in Section
     6(a) of the Employment Agreement. Instead, the parties have mutually agreed
     to end their current relationship in accordance with Section 6(d) of the
     Employment Agreement on the terms and conditions set forth herein.

2)   CONSIDERATION TO MR. STOLL: The Company shall make the following payments
     and provide the following additional consideration to Mr. Stoll:

     a)   SALARY AND BENEFITS CONTINUATION: Upon the separation of Mr. Stoll's
          employment with the Company, the Company agrees to pay Mr. Stoll all
          accrued but unpaid base salary through January 31, 2001. In addition,
          the Company agrees to the following:

          i)   SALARY. The Company agrees that beginning February 1, 2001
               through January 31, 2003, Mr. Stoll shall receive continuation of
               his salary at an annual rate of Five Hundred Sixty Nine Thousand,
               Four Hundred Forty Dollars ($569,440) from which all applicable
               withholdings shall be made. This two (2) year "Salary
               Continuation" period will be paid out over twenty-six (26) pay
               periods for each year. At FMC's option, the Company may elect to
               provide the Salary Continuation referenced in this Section
               2(a)(i) in a lump sum (the "Lump Sum Election"), in which event
               Mr. Stoll shall forego the continuation of his life insurance and
               medical benefits provided in Section 2(a)(ii).

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          ii)   MEDICAL AND DENTAL COVERAGE, AND LIFE INSURANCE; NO LUMP SUM
                ELECTION. For as long as Mr. Stoll is receiving the Salary
                Continuation, and provided that Mr. Stoll has not received the
                Lump Sum payment, the Company agrees that Mr. Stoll shall
                receive continuation at the Company's expense of any coverage
                under FMC's medical and dental plans, such coverage to be
                provided to Mr. Stoll on the same basis and to the same extent
                as the coverage provided Mr. Stoll during his employment,
                subject to any plan changes made during such Salary Continuation
                period that also apply to all other participants in such plans.
                Mr. Stoll's life insurance benefits will similarly continue at
                the Company's expense during the Salary Continuation. Any
                conversion of life insurance at the end of that period (or upon
                a Lump Sum payment) may be arranged through the Corporate Human
                Resources Department.

          iii)  MEDICAL AND DENTAL COVERAGE, AND LIFE INSURANCE; LUMP SUM
                ELECTION. In the event that Mr. Stoll receives the Lump Sum
                payment as provided in Section 2(a)(i), he shall forego
                continuation of the coverage specified in Section 2(a)(ii); it
                being understood, however, that Mr. Stoll shall have the right
                to elect to pay for coverage himself under COBRA. FMC will send
                Mr. Stoll the documents necessary for such COBRA election.

          iv)   LONG AND SHORT TERM DISABILITY BENEFITS. Mr. Stoll's long and
                short term disability benefits shall cease as of January 31,
                2001.

          v)    401(k) PLAN. Contributions to FMC's 401(k) Plan may be withdrawn
                from the plan by Mr. Stoll following Mr. Stoll's termination of
                employment. Mr. Stoll may not make contributions to the Plan
                during the Salary Continuation period.

          vi)   PENSION PLAN. Mr. Stoll will stop accruing benefit service under
                the Pension Plan effective January 31, 2001.

          vii)  DEFERRED COMPENSATION PLAN. Mr. Stoll's account balance under
                the Deferred Compensation Plan will be paid to him within sixty
                (60) days of the Separation Date.

          viii) TAX PREPARATION. Mr. Stoll shall be reimbursed for expenses
                associated with individual income tax preparation up to a total
                of $2,000 per year for the years 1999 and 2000.

          ix)   LEGAL FEES. Mr. Stoll shall be entitled to reimbursement for
                legal fees incurred in connection with this Separation Agreement
                pursuant to paragraph 8 of the Employment Agreement.

     b)   STOCK OPTIONS: Mr. Stoll shall also on the Separation Date be vested
          in Options consisting of Sixty Thousand (60,000) Fresenius Medical
          Care AG Preference Shares. The Company and FMCAG agree that, as
          provided in Mr. Stoll's Employment Agreement, Mr. Stoll is granted up
          to one (1) year from the Separation Date in which to exercise the
          Vested Options, PROVIDED that Ben Lipps, or his successor, will
          recommend to the Management Board of FMCAG (the "Management Board"),
          including but not limited to recommending to the Management Board
          through an oral and written presentation in accordance with the normal
          operating procedures of the Management Board, that Mr. Stoll be
          granted two (2) years from the date of this Agreement to exercise such
          Vested Options.

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     c)   VACATION/PTO TIME: Mr. Stoll will receive on or before the Separation
          Date a payout of all accrued but unpaid vacation PTO time to which he
          is entitled under Company policy.

     d)   EXPENSE REIMBURSEMENT: The Company acknowledges that Mr. Stoll has
          incurred expenses on behalf of the Company which have not yet been
          reimbursed, and, in accordance with the Company's policies, the
          Company will reimburse Mr. Stoll within ten (10) business days of the
          submission of documented proof of such expenses to Brian O'Connell,
          Vice President of Human Resources.

3)   MUTUAL RELEASE: The Company and its affiliates, predecessors, successors,
     assigns, officers, directors, representatives and attorneys (the "Employer
     Parties") hereby irrevocably and unconditionally release, acquit and
     forever discharge Mr. Stoll and his successors, assigns, representatives
     and attorneys, and all persons acting by, through, under or in concert with
     him (collectively "Employee Parties"), from any and all charges,
     complaints, claims, liabilities, obligations, promises, agreements,
     controversies, damages, actions, causes of action, suits, rights, demands,
     costs, losses, debts and expenses (including attorney's fees and costs
     actually incurred), of any nature whatsoever, known or unknown
     (collectively "Employer Claims"), which the Employer Parties now have, own,
     or hold, or claim to have, own, or hold, or which the Employer Parties at
     any time had, owned, or held, or claimed to have, own, or hold against each
     or any of the Employee Parties from the beginning of time until the
     Effective Date of this Agreement other than any Employer Claims arising
     with respect (i) to this Separation Agreement, the Loan Agreement and Form
     of Note attached as Exhibit A hereto and incorporated by reference herein,
     and any agreements executed in connection or simultaneously herewith, and
     (ii) that certain Non-Disclosure and Non-Competition Agreement dated as of
     October 23, 1998 between FMC and Mr. Stoll (the "Non-Disclosure and
     Non-Competition Agreement").

     The Employee Parties hereby irrevocably and unconditionally release, acquit
     and forever discharge the Employer Parties from any and all charges,
     complaints, claims, liabilities, obligations, promises, agreements,
     controversies, damages, actions, causes of action, suits, rights, demands,
     costs, losses, debts and expenses (including attorney's fees and costs
     actually incurred), of any nature whatsoever, known or unknown
     (collectively "Employee Claims"), which the Employee Parties now have, own,
     or hold, or claim to have, own, or hold, or which the Employee Parties at
     any time had, owned, or held, or claimed to have, own, or hold against each
     or any of the Employer Parties from the beginning of time until the
     Effective Date of this Agreement other than any Employee Claims arising
     with respect (i) to this Separation Agreement and any agreements executed
     in connection or simultaneously herewith, and (ii) the Non-Disclosure and
     Non-Competition Agreement.

4)   UNEMPLOYMENT BENEFITS: The Company agrees that it will not protest any
     claim Mr. Stoll may file for unemployment compensation.

5)   RETURN OF PROPERTY: Mr. Stoll expressly agrees that by the Separation Date
     he will return to the Company, and will not retain copies of, all property
     of the Company including, but not limited to, any and all files, computers,
     computer equipment and software and diskettes, documents, papers, records,
     accords, notes, agenda, memoranda, plans, calendars and other books and
     records of any kind and nature whatsoever containing information concerning
     the Company or its customers or operations, other than copies of materials
     that are available to the general public and materials that came into Mr.
     Stoll's possession outside the scope of his employment with the Company.

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6)   NON DISCLOSURE: Mr. Stoll acknowledges and affirms that he continues to be
     bound and will abide by the provisions of the Non-Disclosure and
     Non-Competition Agreement .

7)   BINDING NATURE OF AGREEMENT: This Agreement shall be binding upon each of
     the Parties and upon their heirs, administrators, representatives,
     executors, successors and permitted assigns, and shall inure to the benefit
     of each party and to their heirs administrators, representatives,
     executors, successors and permitted assigns.

8)   NO ORAL MODIFICATION: This Agreement may not be changed orally and no
     modification, amendment or waiver of any provision contained in this
     Agreement, or any future representation, promise or condition in connection
     with the subject matter of this Agreement shall not be binding upon any
     party hereto unless made in writing and signed by such party.

9)   SEVERABILITY: In the event that any provision of this Agreement or the
     application thereof should be held to be void, voidable, unlawful or, for
     any reason unenforceable, the remaining portion and application shall
     remain in full force and effect, and to that end the provisions of this
     Agreement are declared to be severable.

10)  GOVERNING LAW: This Agreement is made and entered into, and shall be
     subject to, governed by, and interpreted in accordance with the laws of the
     Commonwealth of Massachusetts and shall be fully enforceable in the courts
     of that state, without regard to principles of conflict of laws. The
     Parties (i) agree that any suit, action or other legal proceeding arising
     out of this Agreement may be brought in the United States District Court
     for the District of Massachusetts, or if such court does not have
     jurisdiction or will not accept jurisdiction, in any court of general
     jurisdiction in Suffolk County, Massachusetts; (ii) consent to the
     jurisdiction of any such court; and (iii) waive any objection which they
     may have to the laying of venue in any such court. The parties also consent
     to the service of process, pleadings, notices or other papers by regular
     mail, addressed to the party to be served, postage prepaid, and registered
     or certified with return receipt requested.

11)  NOTICES: All notices, requests, consents, approvals and other
     communications required or permitted under this Agreement ("Notices") shall
     be in writing and shall be delivered to the addresses listed below, by
     mail, by hand, or by facsimile transmission, unless otherwise provided in
     this Agreement.

     In the case of Mr. Stoll:

         Roger G. Stoll
         2141 Oyster Harbor
         Osterville, MA 02655
         Phone: 508 428-3117

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     In the case of Fresenius Medical Care Holdings, Inc.:

        Fresenius Medical Care Holdings, Inc.95 Hayden Avenue
        Lexington, Massachusetts 02420
        Attention: Ronald J. Kuerbitz, Senior Vice President and General Counsel

        Phone: 781 402-4003
        FAX: 781 402-9713

     Any party may change its address or facsimile number for notification
     purposes by giving the other parties notice, in accordance with the notice
     provisions set forth in this Section, of the new address or facsimile
     number and the date upon which it will become effective.

12)  NO ASSIGNMENT: Neither this Agreement nor any portion hereof is assignable,
     except with the prior written consent of the other Party. The Parties
     represent, warrant and covenant that they have not previously assigned or
     transferred, or purported to assign or transfer, to any individual or
     entity, any of the rights being released herein.

13)  COUNTERPARTS, ENTIRE AGREEMENT: This Agreement may be executed in
     counterparts, and each counterpart, when executed, shall have the effect of
     a signed original. This Agreement constitutes the entire agreement between
     the parties, with the exception of the Non-Disclosure and Non-Competition
     Agreement, and supersedes all existing agreements between them, whether
     oral or written, with respect to the subject matter hereof.

14)  ACKNOWLEDGMENT OF REVOCATION RIGHTS. Mr. Stoll certifies that he has read
     the terms of this Agreement. The execution hereof by Mr. Stoll shall
     indicate that this Agreement conforms to Mr. Stoll's understandings and is
     acceptable to him as a final agreement. It is further understood and agreed
     that Mr. Stoll has been advised of the opportunity to consult with counsel
     of his choice and that he has been given a reasonable and sufficient period
     of time of no less that twenty one (21) days in which to consider and
     return this document. It is further agreed and understood that upon Mr.
     Stoll's execution and return of this document, he is thereafter permitted
     to revoke the Agreement at any time during a period of seven (7) days
     following his execution hereof. This agreement shall not be effective until
     the seven (7) day revocation period has expired, but upon expiration of
     such period shall be effective as of the Effective Date. To be effective,
     the revocation must be in writing and must be hand-delivered or telecopied
     to counsel for the Company within the seven (7) day period.

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     WHEREFORE, intending to be legally bound, the parities have agreed to the
     aforesaid terms and indicate their agreement by signing below.

     [PLEASE READ CAREFULLY.] THIS AGREEMENT IS A LEGAL DOCUMENT AND INCLUDES A
     RELEASE OF ALL KNOWN AND UNKNOWN CLAIMS, INCLUDING WITHOUT LIMITING THE
     GENERALITY OF THE FOREGOING, ALL CLAIMS ARISING UNDER TITLE VII OF THE
     CIVIL RIGHTS ACT OF 1964, AS AMENDED, THE AGE DISCRIMINATION IN EMPLOYMENT
     ACT, AS AMENDED, THE EMPLOYEE RETIREMENT INCOME SECURITY ACT, AS AMENDED,
     AND CHAPTER 93A AND 151B OF THE MASSACHUSETTS GENERAL LAWS.

     BY SIGNING THIS AGREEMENT, I ACKNOWLEDGE AND AFFIRM THAT I AM COMPETENT,
     THAT I HAVE BEEN AFFORDED A TIME PERIOD OF TWENTY ONE (21) DAYS TO REVIEW
     AND CONSIDER THIS AGREEMENT AND HAVE BEEN ADVISED TO DO SO WITH AN ATTORNEY
     OF MY CHOICE. THAT I HAVE READ AND UNDERSTAND AND ACCEPT THIS DOCUMENT AS
     FULLY AND FINALLY WAIVING AND RELEASING ANY AND ALL CLAIMS, DEMANDS,
     DISPUTES AND ANY DIFFERENCES OF ANY KIND WHATSOEVER WHICH I MAY HAVE HAD OR
     NOW HAVE AGAINST THE COMPANY ARISING OUT OF OR RELATING TO MY EMPLOYMENT
     WITH THE COMPANY, COMPENSATION AND BENEFITS WITH THE COMPANY, SEPARATION
     FROM EMPLOYMENT OR OTHERWISE, EXCEPT AS PROVIDED HEREIN, THAT NO
     REPRESENTATIONS, PROMISES OR INDUCEMENTS HAVE BEEN MADE TO ME, EXCEPT AS
     PROVIDED HEREIN, THAT NO REPRESENTATIONS, PROMISES OR INDUCEMENTS HAVE BEEN
     MADE TO ME EXCEPT AS SET FORTH IN THIS AGREEMENT, AND THAT I HAVE SIGNED
     THIS DOCUMENT FREELY AND VOLUNTARILY, INTENDING TO BE LEGALLY BOUND BY ITS
     TERMS, AND WITH FULL UNDERSTANDING OF ITS CONSEQUENCES.

     ROGER G. STOLL

     /s/ Roger G. Stoll                                            2-12-01
     -----------------------                                    ---------------
                                                                    Date

     FRESENIUS MEDICAL CARE HOLDINGS, INC.
     d/b/a FRESENIUS MEDICAL CARE NORTH AMERICA

     /s/ Ronald J. Kuerbitz                                        2-12-01
     -------------------------------                            ----------------

By: Ronald J. Kuerbitz, Senior Vice President

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Exhibit A

                                       7<PAGE>   1
                                                                   EXHIBIT 10.12

                                 LOAN AGREEMENT

     AGREEMENT made and entered into as of the 31st day of January, 2001, by and
between Roger G. Stoll, an individual with his principal residence at 2141
Oyster Harbor Osterville, MA 02655 (hereinafter referred to as the "Borrower",
and Fresenius Medical Care Holdings, Inc., a New York corporation having its
executive office and principal place of business at 95 Hayden Avenue Lexington,
MA 02420 (hereinafter referred to as the "Lender").

     NOW, THEREFORE, in consideration of mutual covenants set forth herein and
for other good and valuable consideration, the parties hereto have agreed, and
do hereby agree, as follows:

SECTION 1. LOAN AGREEMENT

On the terms and conditions set froth herein, the Lender agrees to lend to the
Borrower, a sum equal to the amount of state and federal taxes (the "Taxes") due
and payable as a result of the sale of the Borrower's former principal residence
in Connecticut (the "Loan").

SECTION 2. CONDITIONS OF NOTE

     (i)  Borrower's execution and delivery to Lender of a Promissory Note,
          hereinafter referred to as the "Note", in the form of EXHIBIT A hereto
          attached evidencing the Loan. The Borrower shall have the right to
          repay the Loan in whole or in part at any time, or from time to time,
          without penalty.
     (ii) Lender's obligation to fund the Loan shall be conditioned on Lender's
          prior receipt from Borrower of evidence in the form and substance
          reasonably satisfactory to Lender of Borrower's obligation to pay the
          Taxes.

SECTION 3. EVENTS OF DEFAULT

3.1  Payment of Note. The Note shall become immediately due and payable in full
     upon the occurrence of the following event of default (an "Event of
     Default"): Commencement by Borrower of a voluntary case under Title 7 or 13
     of the United States Bankruptcy Code as from time to time in effect; have
     filed against him a petition commencing an involuntary case under said
     Title 7 or 13 which is not stayed or dismissed within 60 days after its
     filing; make an assignment for the benefit of, or enter into a composition
     with, Borrower's creditors, or appoint or consent to the appointment of a
     receiver or other custodian for all or a substantial part of Borrower's
     property.

3.2  Waiver of notice. The Borrower hereby waives presentment for payment,
     demand, protest, notice of protest and all other demands and notices in
     connection with the

                                  Page 1 of 4
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     delivery, acceptance, performance, defaults, or enforcement of this Loan
     Agreement and Note; and the Borrowers expressly assents to any extension or
     postponement of the time of payment or other indulgence.

SECTION 4. MISCELLANEOUS

4.1  The Lender shall not by any act of omission or commission be deemed to
     waive any of its rights or remedies hereunder unless such waiver be in
     writing and signed by the Lender, and then only to the extent specifically
     set forth therein; a waiver on one event shall not be construed as
     continuing or as a bar to or waiver of such right or remedy on a subsequent
     event.

4.2  This Agreement may not be assigned by the Borrower. This Agreement shall be
     governed by the laws of the Commonwealth of Massachusetts.

     Executed at Lexington, Massachusetts, on the day and year first above
     written.

LENDER

Fresenius Medical Care Holdings, Inc.

By: /s/ Ronald J. Kuerbitz
    ----------------------

Its: Senior Vice President

BORROWER

By: /s/ Roger G. Stoll
    ------------------
    Roger G. Stoll

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                                    EXHIBIT A
                                 PROMISSORY NOTE

          $                                             Lexington, Massachusetts
                                                                          [date]

     FOR VALUE RECEIVED Roger G. Stoll, an individual ("the Maker"), promises to
pay to the order of Fresenius Medical Care Holdings, Inc., a New York
corporation ("FMC") the principal amount of ____________________________________
("Principal") pursuant to that certain Loan Agreement dated as of January 31,
2001 by and between FMC and the Maker (the "Loan Agreement"), with interest, at
the rate hereinafter set forth, on the daily balance of all unpaid Principal,
from the date hereof until payment in full of all Principal hereunder.
Capitalized terms used but not otherwise defined herein shall have the meaning
ascribed to them in the Loan Agreement.

     This Note shall bear interest per annum on the principal balance from time
to time remaining unpaid at a rate equal to seven and three-quarters percent (7
3/4%) per annum. All past due payments shall bear interest at the lesser of
eighteen percent (10%) per annum or the maximum rate permitted by then
applicable law. All Principal and accrued interest shall be due and payable on
January 31, 2003.

     All outstanding Principal and all interest accrued thereon shall be
immediately due and payable in full at the option of FMC on the occurrence of an
Event of Default under Section 3 of the Loan Agreement.

     Payments of both Principal and interest shall be made, in immediately
available funds, via check or electronic funds transfer to such bank account(s),
or at such other address as the holder of this Note may from time to time
designate.

     The Maker agrees to pay, to the extent permitted by law, all costs and
expenses of collection, including, without limitation, reasonable attorneys'
fees, incurred or paid by FMC in enforcing its rights under this Note, whether
or not litigation is commenced.

     This promissory note is the "Note" referred to in, and is entitled to the
benefits of, the Loan Agreement. This Note is subject to prepayment and its
maturity may be accelerated upon the occurrence of an Event of Default, all as
provided in the Loan Agreement. The obligations of the Maker hereunder shall not
be subject to any defense, setoff, counterclaim, recoupment, or termination
whatsoever based upon the invalidity, illegality, or unenforceability of any
other agreements between the Maker and FMC or otherwise.

     This Note shall be binding upon the Maker and its successors and assigns.
The invalidity or unenforceability of any provision of this Note shall not
affect the other provisions hereof and the remaining provisions of this Note
shall remain operative and in full force and effect.

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     This Note shall be governed by and construed in accordance with the laws of
the Commonwealth of Massachusetts without giving effect to any choice or
conflict of law provision or rule. The Maker hereby waives presentment, demand,
notice, protest and all other demands and notices in connection with the
delivery, acceptance, performance and enforcement of this Note, except as
specifically otherwise provided herein and assents to extensions of the time of
payment, or forbearance or other indulgence without notice. No right, power or
remedy conferred hereby shall be exclusive of any other right, power or remedy
referred to herein or now or hereafter available.

     The Maker may not assign its obligations under this Note without the
express written consent of the holder hereof in its sole discretion.

     This Note is executed, as an instrument under seal, as of the day and year
first above written.

                                                     ---------------------------
                                                     Roger G. Stoll

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