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                                                                 EXHIBIT 10.12

                    AMENDMENT TO PURCHASE AND SALE AGREEMENT

         THIS AMENDMENT TO PURCHASE AND SALE AGREEMENT (the "Amendment") is made
and entered into effective as of December 31, 1996, (the "Effective Date of the
Amendment"), by and between United Wisconsin Services, Inc., a Wisconsin
business corporation ("UWS") and Midelfort Clinic, Ltd., Mayo Health System, a
Wisconsin corporation ("Clinic") (Individually, a "Party", and collectively the
"Parties").

                                    RECITALS

         A. UWS and Clinic (or its affiliate or successor) are parties to that
certain purchase and sale agreement dated January 1, 1992, (the "Agreement"),
pursuant to which Clinic sold all the outstanding shares of Midelfort Health
Plan, Inc. ("MHP").

         B. UWS and Clinic (or its affiliate or successor) are also parties to
that certain joint venture agreement dated January 1, 1992, which was superseded
by an Amended and Restated Joint Venture Agreement of even date herewith (the
Amended and Restated "Joint Venture Agreement").

         C. Midelfort Health Plan, Inc. (MHP) has changed its name to Valley
Health Plan, Inc. (VHF)

         D. In consideration for extending the term of the Joint Venture
Agreement and amending the Joint Venture Agreement in other respects, the
Parties desire to extend the term of the Agreement and amend the Agreement in
certain respects as set forth herein.

         NOW, THEREFORE, in consideration of the premises and the mutual
promises set forth in this Amendment, and other good and valuable consideration,
the receipt and adequacy of which are hereby acknowledged, the parties hereby
agree as follows:

         1. ASSIGNMENT. The Parties hereby acknowledge that Midelfort Clinic,
Ltd. has been acquired by Mayo Foundation for Medical Education and Research
("Mayo"), and hereby consents to the assignment by Midelfort Clinic, Ltd. to
Midelfort Clinic, Ltd., Mayo Health System, of all of its right, title and
interest in, to and under the Agreement.

         2 . MODIFICATION OF AGREEMENT. The Parties hereby agree that the
Clinic's option to repurchase shall be in effect for the Initial Term of the
Amended and Restated Joint Venture Agreement, and may be exercised effective as
of December 31, 1999, subject to the modifications set forth in this Amendment,
and that Section 10.1 and Section 10.4 are hereby amended to read in its
entirety as follows:

October 25, 1996                                                          Page 1
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                  10.1 Either at the end of the Initial Term of the Joint
         Venture, as defined in Section 7.1 of the Amended and Restated Joint
         Venture Agreement, or termination of the Joint Venture whichever occurs
         earlier, the Clinic shall have the option to repurchase one hundred
         percent of the outstanding shares of VHP stock

                  10.4 The Clinic shall exercise this option to repurchase by
         giving written notice to Thomas R. Hefty as president of UWS at least
         One Hundred and Eighty (180) days but no more than Two Hundred and
         Seventy (270) days in advance of the effective date (the "Exercise
         Date"). The repurchase shall be effective on December 31, 1999, or the
         date of termination of the Joint Venture Agreement, whichever occurs
         earlier. (the "Repurchase Date").

         3. ADDITIONS TO AGREEMENT. The Parties hereby add the following
provisions to the Agreement.

                  10.5 In the event that the Clinic exercises its option to
         repurchase, UWS shall, within Forty-five (45) business days after the
         end of the month in which the Exercise Date occurs, provide Clinic with
         the following: (i) statement of all assets held by VHP and all
         liabilities of VHP as of the end of the month in which the Exercise
         Date occurs and (ii) balance sheet and statements of income and
         expenditures for-VHP as of the end of the month in which the Exercise
         Date occurs.

                  10.6 From the Exercise Date through the closing date of such
         repurchase (the "Interim Period"), UWS shall not, in connection
         with-VHP, without the prior written consent of Clinic, (a) enter into
         any contract or commitment with respect to VHP extending beyond the
         closing date, other than sales or purchases made in the ordinary course
         of its business; (b) waive any rights of any substantial value or sell,
         assign or transfer any of the assets of VHP other than in the ordinary
         course of business; (c) incur any obligations or liabilities (absolute
         or contingent) other than current liabilities incurred and obligations
         under contracts entered into in the ordinary course of business; (d)
         encumbrance any assets, tangible or intangible, other than the lien of
         current property taxes not due and payable; (e) sell, assign or
         transfer any of the assets of VHP or cancel any debts or claims; (f)
         increase the salaries or other fringe benefits made available to the
         employees of VHP, institute any bonus, benefit, profit sharing, stock
         option, pension, retirement plan or similar arrangements for the
         benefit of the employees of VHP, or make any changes in any such plans
         or arrangements presently existing; or (g) enter into any other
         transactions or series of transactions other than in the ordinary
         course of business.

October 25, 1996                                                          Page 2
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                  10.7 UWS shall, within Ninety (90) business days after the
         Repurchase Date, provide Clinic with the following: (i) statement of
         all assets held by VHP and all liabilities of VHP as of the Repurchase
         Date; and (ii) balance sheet and statements of income and expenditures
         for VHP as of the current calendar year to the Repurchase Date.

                  10.8 UWS represents and warrants that the financial statements
         provided to Clinic pursuant to Sections 10.5 and 10.7 hereof (i) will
         be in accordance with the books and records of VHP which books and
         records are complete and accurate in all material respects, (ii) will
         present fairly and accurately in all material respects the financial
         condition of VHP as of the dates of the balance sheets, (iii) present
         or will present fairly and accurately in all material respects the
         results of operations of VHP for the periods covered by such
         statements, and (iv) have been or will be prepared in all material
         respects on a basis consistent with the preparations of VIII's prior
         years' financial statements.

         4. REFERENCES. All references in this Amendment to the Agreement shall
mean and include, as appropriate, both the original Agreement between the
Parties, and all amendments which are in writing and have been executed by the
Parties. All references in this Amendment to the Agreement or the Agreement to
Midelfort Health Plan, Inc. shall also include reference to Valley Health Plan,
Inc.

         5. CONTINUED EFFECT. Except as otherwise provided in this Agreement,
but subject to any other amendments to the Agreement which are in writing and
have been executed by the Parties, the Agreement shall remain in full force and
effect.

         IN WITNESS WHEREOF, the Parties have caused this Amendment to be
executed as of the Effective Date by their respective representatives.

Attest:                                   UNITED WISCONSIN SERVICES, INC.

/s/ John M. Drace                         BY /s/ Thomas R. Hefty
--------------------------------             -----------------------------------

                                          TITLE
                                               ---------------------------------

Attest:                                   MIDELFORT CLINIC, LTD., MAYO
                                          HEALTH SYSTEM

/s/ John M. Drace                         BY /s/ William C. Rupp, M.D.
--------------------------------             -----------------------------------

                                          TITLE
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October 25, 1996                                                          Page 3<PAGE>
                                                                   EXHIBIT 10.13

                 SECOND AMENDMENT TO PURCHASE AND SALE AGREEMENT

         THIS SECOND AMENDMENT TO PURCHASE AND SALE AGREEMENT (the "Amendment")
is made and entered into effective as of January 1, 2000, by and between United
Wisconsin Services, Inc., a Wisconsin business corporation ("UWS") and Midelfort
Clinic, Ltd., Mayo Health System, a Wisconsin corporation (the "Clinic"),
(individually, a "Party" and collectively, the "Parties").

                                    RECITALS

         WHEREAS, UWS and the Clinic (or its affiliate or successor) are parties
to that certain purchase and sale agreement dated January 1, 1992 and amended
effective December 31, 1996 (the "Agreement"), pursuant to which the Clinic sold
all the outstanding shares of Midelfort Health Plan, Inc. (n/k/a Valley Health
Plan, Inc.) to UWS;

         WHEREAS, UWS and the Clinic (or its affiliate or successor) are also
parties to that certain joint venture agreement dated January 1, 1992, which was
superseded by an Amended and Restated Joint Venture Agreement dated January 1,
1997, and which has been superseded by a Second Amended and Restated Joint
Venture Agreement, dated January 1, 2000 (the "Second Amended and Restated Joint
Venture Agreement");

         WHEREAS, in consideration for extending the term of the Joint Venture
Agreement and amending the Joint Venture Agreement in other respects, the
Parties desire to extend the term of the Agreement as set forth herein.

         NOW, THEREFORE, in consideration of the premises and the mutual
promises set forth in this Amendment, and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the Parties hereby
agree as follows:

         1. REPURCHASE OPTION. The Parties hereby agree that the Clinic's option
to repurchase shall be in effect for the Initial Term of the Second Amended and
Restated Joint Venture Agreement and may be exercised effective December 31,
2002 subject to the modifications set forth in this Amendment, and that
Section 10.1 and Section 10.4 are hereby amended to read it their entirety as
follows:

                  10.1 Either at the end of the Initial Term of the Second
         Amended and Restated Joint Venture, or termination of the joint
         venture, whichever occurs earlier, the Clinic shall have the option to
         repurchase one hundred percent (100%) of the outstanding shares of VHP
         stock.

                  10.4 The Clinic shall exercise this option to repurchase by
         giving written notice to Thomas R. Hefty, as President of UWS, at least
         One Hundred and Twenty (120) days but no more than One Hundred and
         Thirty (130) days in advance of the effective date (the

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         "Exercise Date"). The repurchase shall be effective on December 31,
         2002, or the date of termination of the Second Amended and Restated
         Joint Venture Agreement, whichever occurs earlier (the "Repurchase
         Date").

         2. REFERENCES. All references in this Amendment to the Joint Venture
Agreement shall mean and include, as appropriate, both the original joint
venture agreement between the Parties, and all amendments and restatements which
are in writing and have been executed by the Parties.

         3. CONTINUED EFFECT. Except as otherwise provided in this Amendment,
and subject to any other amendments which are in writing and have been executed
by the Parties, the Agreement shall remain in full force and effect.

         IN WITNESS WHEREOF, the Parties have caused this Amendment to be
executed as of the date above written by their respective representatives.

Attest:                                        UNITED WISCONSIN SERVICES, INC.

                                               By: /s/ Thomas R. Hefty
-----------------                                 ------------------------------

                                               Title:
                                                     ---------------------------

Attest:                                        MIDELFORT CLINIC, LTD., MAYO
                                               HEALTH SYSTEM

                                               By: /s/ William C. Rupp, M.D.
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                                               Title:
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