March 29, 1996

Mr. Albert J. Costello
Chairman, President and
   Chief Executive Officer
W. R. Grace & Co.
One Town Center Road
Boca Raton, Florida 33486-1010

Dear Al:

                  The purpose of this letter is to confirm our understanding
with respect to my Employment Agreement ("Employment Agreement"), dated as of
April 1, 1991, with a subsidiary of W. R. Grace & Co. ("Grace"), as follows:

                  1. I hereby conditionally rescind the notice previously
given to you that I had elected to convert the Employment Agreement into a
consulting agreement upon the terms and conditions set forth in Section 7 of
the Employment Agreement.

                  2. In consideration of such conditional rescission, Grace
agrees to extend the Employment Agreement, and I hereby agree to remain in
Grace's employ, until the first to occur of (a) December 31, 1996 or (b) the
disposition of National Medical Care, Inc. ("NMC") by Grace, whether or not
such disposition is in the form of the proposed transaction between Grace and
Fresenius AG ("Fresenius"). During the period that the Employment Agreement
remains in effect, both parties shall continue to be bound by the provisions
thereof (including without limitation the provisions under which I have the
right to convert the Employment Agreement into a consulting agreement);
provided, however, that:

                  (a) I understand and agree that I will not be a participant
         in Grace's Long-Term Incentive Program for the 1996-1998 Performance
         Period or any subsequent Performance Period and that I will not be
         eligible to receive any portion of the pool that has been established
         to provide NMC employees with "stay bonuses" in connection with
         Grace's proposed disposition of NMC (I understand, however, that I
         will be eligible to participate in the portions of the NMC incentive
         compensation pool relating to annual performance and cash flow
         performance, respectively); and

                  (b) In the event the proposed transaction with Fresenius is
         not consummated by December 31, 1996, or in the event that such
         transaction is so consummated but the New Agreement (as defined
         below) is not executed by me and Fresenius by December 31, 1996, the
         conditional rescission referred to above will automatically be
         revoked, and, effective January 1, 1997, the Employment Agreement
         will be converted into a consulting agreement upon the terms and
         conditions set forth in Section 7 of the Employment Agreement.




     





                  3. Grace management will recommend that I be nominated to
stand for election as a Class II Director of Grace at its 1996 Annual Meeting
of Shareholders, for a term expiring at the 1997 Annual Meeting of
Shareholders. However, I agree to resign, and I hereby tender my resignation,
as a director of Grace, such resignation to be effective on the date of
termination of my employment by Grace as specified in paragraph 2 above.

                  4. In connection with the transaction with Fresenius
referred to in paragraph 2 above, I expect to enter into an agreement ("New
Agreement") providing for my service as an employee of and/or consultant to
NMC (or another affiliate of Fresenius) following completion of such
transaction. I hereby agree as follows in connection with the New Agreement:

                  (a) I agree to negotiate the terms of the New Agreement in
         good faith with representatives of Fresenius.

                  (b) Upon the effectiveness of the New Agreement, the
         Employment Agreement shall terminate and be of no further force and
         effect, except as specified in Section 4.2 thereof (which contains
         covenants as to confidentiality), and I shall have no right to serve
         as a consultant to Grace.

                  If the foregoing correctly sets forth our understanding,
please sign this letter and the accompanying copy as indicated below and
return one copy to me.

                                                     Very truly yours,



                                                     Constantine L. Hampers


Agreed as set forth above:

W. R. Grace & Co.


By: -----------------------------
    Albert J. Costello
    Chairman, President and
      Chief Executive Officer