AMENDMENT TO EMPLOYMENT AGREEMENT

EXHIBIT 10(c)

AMENDMENT TO EMPLOYMENT AGREEMENT

This Amendment, effective as of August 5, 2005, is made by and between William W. McGuire, M.D. (“Executive”) and UnitedHealth Group Incorporated (“UnitedHealth Group” or the “Company”) and amends that certain employment agreement, dated October 13, 1999, as amended on February 13, 2001 (the “Employment Agreement”), between UnitedHealth Group (formerly known as United HealthCare Corporation).

WHEREAS, the parties previously entered into the Employment Agreement to provide for Executive’s services as Chief Executive Officer of the Company;

WHEREAS, pursuant to the Company’s existing policies, Executive is eligible for retirement (“Retirement”);

WHEREAS, it is the desire of the Company and Executive to provide for Executive’s continued services as Chief Executive Officer, notwithstanding Executive’s eligibility for Retirement;

WHEREAS, Executive and the Company desire to amend Executive’s Employment Agreement on the terms set forth herein.

NOW, THEREFORE, in consideration of the representations, warranties, covenants and agreements contained in this Agreement and other good and valuable consideration, the sufficiency of which is hereby acknowledged, the parties hereto agree as follows:

1. COMPENSATION. Sections 2 (a) and 2(b) of the Employment Agreement, are hereby amended and restated in their entirety to read as follows:

prior right to an annual stock option grant under Section 2(b) of the Employment Agreement, and (ii) in no event shall the aggregate amount of Equity Grants to Executive in any calendar year be in an amount less than or contain terms and conditions that are less favorable than the aggregate amount of Equity Grants granted generally to any other senior officer of UnitedHealth Group in that calendar year. Each Equity Grant shall be subject to the terms and conditions of UnitedHealth Group’s 2002 Stock Incentive Plan, or any substitute or similar successor plan (the “Stock Plan”). The form of award for each Equity Grant granted after August 5, 2005 shall include a provision that unless the Employment Agreement, as amended, provides for vesting or exercise periods that are more favorable, upon termination of employment by reason of Retirement, then (i) vesting of such Equity Grant shall continue as if such termination employment had not occurred and (ii) Executive may, at any time within a period of five years after such termination of employment by reason of Retirement or for such other longer period established at the discretion of the Committee, subject to earlier termination upon expiration of such Equity Grant in accordance with its terms and subject to forfeiture upon violation of any restrictive covenant contained in this Agreement, exercise the Equity Grant to the extent of the full number of shares which were exercisable and which Executive was entitled to purchase under the Equity Grant on the date of exercise of the Equity Grant.

2. TERM AND TERMINATION. Sections 3(a) and 3(b) of the Employment Agreement are amended and restated in their entirety to read as follows:

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considered a termination of the Executive’s employment by reason of Retirement in good standing, unless such termination constitutes (A) a “Termination of Employment by Executive Following a Change in Control” as set forth in Section 3(e) of the Employment Agreement, (B) a termination upon death or permanent disability set forth in Section 3(b)(iii) below, or (C) a termination for Cause set forth in Section 3(b)(iv) below.

3. OTHER TERMINATION PROVISIONS. Sections 3(d) and 3(g) of the Employment Agreement (“Termination of Employment by UnitedHealth Group without Cause or by Executive for Good Reason” and “Termination of Employment by Executive without Good Reason”) are hereby deleted in their entirety and any cross-references in the Agreement shall be updated accordingly. Section 3(f) of the Employment Agreement (“Termination of Employment by Executive Upon Retirement”) is hereby amended as follows:

If Executive’s employment with UnitedHealth Group is terminated by UnitedHealth Group or Executive pursuant to Section 3(b)(ii) whether prior to or upon the end of the term of this Agreement, such termination shall be a Retirement of Executive in good standing and upon the termination of Executive’s employment:

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4. TERMINATION OF EMPLOYMENT BY EXECUTIVE FOLLOWING A CHANGE IN CONTROL. Any references to termination of Executive’s employment without Cause in Section 3(e) of the Employment Agreement shall mean any termination of Executive’s employment by UnitedHealth Group for any reason other than for Cause (as set forth in Section 3(b)(v)), death or permanent disability (as set forth in Section 3(b)(iv)) and at any time upon 30 days prior written notice to Executive. Any references to termination of Executive’s employment by Executive for Good Reason in Section 3(e) of the Employment Agreement shall mean any termination of the Employment Agreement for Good Reason (as defined in Section 5(a) of the Employment Agreement) upon 30 days’ prior written notice from Executive to UnitedHealth Group, specifying such Good Reason; provided that such notice is given within 120 days after the initial occurrence of such Good Reason, and provided further that the events giving rise to Good Reason shall not have been remedied as of the date of such notice.

5. PROPERTY RIGHTS, CONFIDENTIALITY, NON-SOLICIT AND NON-COMPETE PROVISIONS. Section 4(d)(iv) of the Employment Agreement is hereby deleted in its entirety.

6. DEFINITIONS. The following definitions contained in Section 5(a) of the Employment Agreement are hereby amended as follows:

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IN WITNESS WHEREOF, this Agreement has been signed by the parties hereto on the date set forth below.

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