UnitedHealth Group (UNH)

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

x    Definitive Proxy Statement

¨    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

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Dear Shareholder:

We cordially invite you to attend our 2009 Annual Meeting of Shareholders. We will hold our meeting on Tuesday, June 2, 2009 at 10:00 a.m. central time at UnitedHealth Group South, 9701 Data Park Drive, Minnetonka, Minnesota.

At this year’s meeting, you will be asked to vote on the election of directors, ratification of Deloitte & Touche LLP’s appointment as our independent registered public accounting firm and one shareholder proposal.

Attached you will find a notice of meeting and proxy statement that contain further information about these items and the meeting itself, including:

Whether or not you attend the meeting in person, we encourage you to vote by Internet or telephone or complete, sign and return your proxy prior to the meeting. If you cannot attend the meeting in person, you may listen to the meeting via webcast. Instructions on how to access the live webcast are included in the attached proxy statement.

Every shareholder vote is important. To ensure your vote is counted at the Annual Meeting, please vote as promptly as possible.

Sincerely,

Stephen J. Hemsley

President and Chief Executive Officer

Richard T. Burke

Chairman of the Board

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Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

x    Definitive Proxy Statement

¨    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

Table of Contents

Dear Shareholder:

We cordially invite you to attend our 2008 Annual Meeting of Shareholders. We will hold our meeting on Thursday, June 5, 2008 at 10:00 a.m. Central Time at The Children’s Theatre Company, 2400 Third Avenue South, Minneapolis, Minnesota.

At this year’s meeting, you will be asked to vote on the election of directors, the approval of the material terms for payment of executive incentive compensation, the approval of an amendment to increase the number of shares of common stock issuable under the UnitedHealth Group 1993 Employee Stock Purchase Plan, ratification of Deloitte & Touche LLP’s appointment as our independent registered public accounting firm, and two shareholder proposals.

Attached you will find a notice of meeting and proxy statement that contain further information about these items and the meeting itself, including:

Whether or not you attend the meeting in person, we encourage you to vote by Internet or telephone prior to the meeting or complete, sign and return your proxy. If you cannot attend the meeting in person, you may view the meeting via webcast. Instructions on how to access the live webcast are included in the attached proxy.

Every shareholder vote is important.

Sincerely,

Stephen J. Hemsley

President and Chief Executive Officer

Richard T. Burke

Chairman of the Board

Table of Contents

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

x    Definitive Proxy Statement

¨    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

Table of Contents

Dear Shareholder:

We cordially invite you to attend our 2007 Annual Meeting of Shareholders. We will hold our meeting on Tuesday, May 29, 2007, at 10:00 a.m., Central Time, at the Minneapolis Convention Center, 1301 Second Avenue South, Room 208C, Minneapolis, Minnesota.

At this year’s meeting, you will be asked to vote on the election of four directors, amendments to our Articles of Incorporation and Bylaws, ratification of Deloitte & Touche LLP’s appointment as our independent registered public accounting firm, and four proposals of shareholders.

Attached you will find a notice of meeting and proxy statement that contain further information about these items and the meeting itself, including:

Whether or not you attend the meeting in person, we encourage you to sign and return your proxy or vote by Internet or telephone prior to the meeting. If you cannot attend the meeting in person, you may view the meeting via webcast. Instructions on how to access the live webcast are included in the attached proxy.

Every shareholder vote is important.

Sincerely,

Stephen J. Hemsley

President and Chief Executive Officer

Richard T. Burke

Chairman of the Board

Table of Contents

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨    Definitive Proxy Statement

x    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

x    Definitive Proxy Statement

¨    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

Table of Contents

Dear Shareholder:

We cordially invite you to attend our 2006 Annual Meeting of Shareholders. We will hold our meeting on Tuesday, May 2, 2006, at 10:00 a.m., Central Time, at UnitedHealth Group Center, 9900 Bren Road East, Minnetonka, Minnesota.

On the following pages we present information about the business to be conducted at the meeting, including information about the nominees for election as members of the Board of Directors. If you cannot attend the meeting, we hope you will still exercise your right as a shareholder and vote. Every shareholder vote is important. We appreciate your cooperation in voting promptly. You may do so by telephone or Internet, or by completing, signing and returning the enclosed proxy in the enclosed envelope, for which no postage is required if mailed in the United States.

Sincerely,

William W. McGuire, M.D.

Chairman and Chief Executive Officer

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UnitedHealth Group Center

9900 Bren Road East

Minnetonka, Minnesota 55343

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Filed by the Registrant    x

Filed by a party other than the Registrant    ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

x    Definitive Proxy Statement

¨    Definitive Additional Materials

¨    Soliciting Material Pursuant to Section 240.14a

UnitedHealth Group Incorporated

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x    No fee required

¨    Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11

¨    Fee paid previously with preliminary materials.

¨    Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing

        for which the offsetting fee was paid previously. Identify the previous filing by registration statement number,

        or the Form or Schedule and the date of its filing.

Table of Contents

Dear Shareholder:

We cordially invite you to attend our 2005 Annual Meeting of Shareholders. We will hold our meeting on Tuesday, May 3, 2005, at 10:00 a.m., Central Time, at UnitedHealth Group Center, 9900 Bren Road East, Minnetonka, Minnesota.

On the following pages we present information about the business to be conducted at the meeting, including information about the nominees for election as members of the Board of Directors. If you cannot attend the meeting, we hope you will still exercise your right as a shareholder and vote. Every shareholder vote is important. We appreciate your cooperation in voting promptly. You may do so by telephone or Internet, or by completing, signing and returning the enclosed proxy in the enclosed envelope, for which no postage is required if mailed in the United States.

Sincerely,

William W. McGuire, M.D.

Chairman and Chief Executive Officer

Table of Contents

UnitedHealth Group Center

9900 Bren Road East

Minnetonka, Minnesota 55343