Exhibit 10.1

MCKESSON CORPORATION

2005 STOCK PLAN

As amended through July 22, 2009

TABLE OF CONTENTS

1. PURPOSE .

     This McKesson Corporation 2005 Stock Plan is intended to provide Employees and Directors the opportunity to receive equity-based, long-term incentives so that the Corporation may effectively attract and retain the best available personnel, promote the success of the Corporation by motivating Employees and Directors to superior performance, and align Employee and Director interests with those of the Corporation’s stockholders.

2. EFFECTIVE DATE .

     This Plan was initially adopted by the Board on May 25, 2005, subject to stockholder approval, which was granted on July 25, 2005. On October 27, 2006, the Board retroactively amended and restated the Plan to comply with proposed regulations issued under Code section 409A. On May 23, 2007, the Plan was amended by the Board to increase the share reserve by 15,000,000 Shares, with such amendment subject to stockholder approval, which was granted on July 25, 2007. On July 23, 2008, the Board approved an amendment and restatement of the Plan regarding the timing of the distribution of Shares underlying grants of Restricted Stock Unit Awards to Outside Directors. On May 26, 2009, the Compensation Committee of the Board approved an amendment of the Plan regarding the circumstances under which a merger or consolidation involving the Corporation would constitute a Change in Control. On May 27, 2009, the Board amended and restated the Plan to increase the share reserve by 14,500,000 Shares, with such amendment and restatement subject to stockholder approval, which was granted on July 22, 2009.

3. ADMINISTRATION .

     (a)  Administration with respect to Outside Directors .

     With respect to Awards to Outside Directors, the Plan shall be administered by (A) the Board or (B) the Committee on Directors and Corporate Governance of the Board; provided that such committee consists solely of Directors who qualify as “non-employee directors” for purposes of Rule 16b-3 promulgated under the Exchange Act. Notwithstanding the foregoing, all Awards made to members of the Committee on Directors and Corporate Governance shall be approved by the Board.

     (b)  Administration with respect to Employees .

     With respect to Awards to Employees, the Plan shall be administered by (A) the Board, (B) the Compensation Committee of the Board; provided that such committee consists solely of Directors who qualify as “outside directors” for purposes of Code section 162(m) and “non-employee directors” for purposes of Rule 16b-3 promulgated under the Exchange Act, or (C) in limited situations, by an officer or officers of Corporation pursuant to Section 3(c) below.

     (c)  Delegation of Authority to an Officer of the Corporation .

          (i) The Board may delegate to a Director the authority to administer the Plan with respect to Awards made to Employees who are not subject to Section 16 of the Exchange Act.

          (ii) The Board may delegate to an officer or officers of the Corporation the authority to administer the Plan with respect to Options granted to Employees who are not subject to Section 16 of the Exchange Act.

     (d)  Powers of the Administrator .

     The Administrator shall from time to time at its discretion make determinations with respect to Employees and Directors who shall be granted Awards, the number of Shares or Share Equivalents to be subject to each Award, the vesting of Awards, the designation of Options as Incentive Stock Options or Nonstatutory Stock Options and other conditions of Awards to Employees and Directors.

     The Administrator shall have the full power and authority, in its sole discretion, to promulgate any rules and regulations which it deems necessary for the proper administration of the Plan, to supervise the administration of the Plan, to make factual determinations relevant to Plan entitlements, to adopt subplans applicable to specified Affiliates or locations and to take all actions in connection with the administration of the Plan as it deems necessary or advisable.

     The Administrator shall have, subject to the terms and conditions and within the limitations of Plan, including the limitations of Section 22, the authority to modify, extend or renew outstanding Awards granted to Employees and Directors under the Plan in a manner that will not cause the Awards that are exempt from the application of Code section 409A to be subject to Code section 409A pursuant to such modification, extension or renewal. Notwithstanding the foregoing, however, no modification of an Award shall, without the consent of the Participant, impair any Award previously granted under the Plan.

     The interpretation and construction by the Administrator of any provisions of the Plan or of any Award shall be final. No member of a Committee shall be liable for any action or determination made in good faith with respect to the Plan or any Award.

4. ELIGIBILITY .

     Subject to the terms and conditions set forth below, Awards may be granted to Employees and Directors. Notwithstanding the foregoing, only employees of the Corporation and its Subsidiaries may be granted Incentive Stock Options.

     (a)  Ten Percent Stockholders .

     An Employee who owns more than 10% of the total combined voting power of all classes of outstanding stock of the Corporation, its parent or any of its Subsidiaries is not eligible to receive an Incentive Stock Option pursuant to this Plan unless the Exercise Price of the Incentive Stock Option is at least 110% of the Fair Market Value of the underlying Shares on the date of the grant and the term of the option does not exceed five years. For purposes of this Section 4(a) the stock ownership of an Employee shall be determined pursuant to Code section 424(d).

     (b)  Number of Awards .

     A Participant may receive more than one Award, including Awards of the same type, but only on the terms and subject to the restrictions set forth in the Plan. Subject to adjustment as provided in Section 16, the maximum aggregate number of Shares or Share Equivalents that may be subject to Full Value Awards granted to a Participant in any fiscal year of the Corporation is 500,000 Shares or Share Equivalents and the maximum number of Shares or Share Equivalents that may be subject to Options or Stock Appreciation Rights granted to a Participant in any fiscal year of the Corporation is 1,000,000 Shares or Share Equivalents.

5. STOCK .

     (a)  Share Reserve .

     Subject to adjustment as provided in Section 16, the aggregate number of Shares subject to Options, Stock Appreciation Rights, Restricted Stock, Restricted Stock Units, Performance Shares or Other Share-Based Awards issued under this Plan shall not exceed 42,500,000 Shares, which Shares shall be Shares of the Corporation’s authorized but unissued or reacquired Common Stock bought on the market or otherwise. If any outstanding Option or Stock Appreciation Right under the Plan for any reason expires or is terminated or any Restricted Stock or Other Share-Based Award is forfeited, then the Shares allocable to the unexercised portion of such Option or Stock Appreciation Right or the forfeited Restricted Stock or Other Share-Based Award may again be available for issuance under the Plan. The following Shares may not again be made available for issuance under the Plan: Shares not issued or delivered as a result of the net exercise of a Stock Appreciation Right or Option; Shares used to pay the withholding taxes related to an Award; or Shares repurchased on the open market with the proceeds of an Exercise Price.

     (b)  Limitation .

     Notwithstanding any other provision of Section 5, for any one Share issued in connection with a Full Value Award or a stock-settled Stock Appreciation Right, that Share and one additional Share shall no longer be available for issuance in connection with future Awards.

6. OPTIONS .

     Options granted to Employees and Directors pursuant to the Plan shall be evidenced by written Option Agreements in such form as the Administrator shall determine. Options shall be designated as Incentive Stock Options or Nonstatutory Stock Options and shall be subject to the following terms and conditions:

     (a)  Number of Shares .

     Each Option shall state the number of Shares to which it pertains, which shall be subject to adjustment in accordance with Section 16.

     (b)  Exercise Price .

     Each Option shall state the Exercise Price, determined by the Administrator, which shall not be less than 100% the Fair Market Value of a Share on the date of grant, except as provided in Section 16.

     (c)  Method of Payment .

     An Option may be exercised, in whole or in part, by giving notice of exercise in the manner prescribed by the Corporation specifying the number of Shares to be purchased. Such notice shall be accompanied by payment in full of the Exercise Price in cash or, if acceptable to the Administrator in its sole discretion (i) in Shares already owned by the Participant (including, without limitation, by attestation to the ownership of such Shares), (ii) by the withholding and surrender of the Shares subject to the Option, or (iii) by delivery (on a form prescribed by the Administrator) of an irrevocable direction to a securities broker approved by the Administrator to sell Shares and to deliver all or part of the sales proceeds to the Corporation in payment of all or part of the purchase price and any withholding taxes. Payment may also be made in any other form approved by the Administrator, consistent with applicable law, regulations and rules.

     (d)  Term and Exercise of Options .

     Each Option shall state the time or times when it may become exercisable. No Option shall be exercisable after the expiration of seven years from the date it is granted.

     (e)  Limitations on Transferability .

     An Option shall, during a Participant’s lifetime, be exercisable only by the Participant. No Option or any right granted thereunder shall be transferable by the Participant by operation of law or otherwise, other than by will, the laws of descent and distribution. Notwithstanding the foregoing, (i) a Participant may designate a beneficiary to succeed, after the Participant’s death, to all of the Participant’s Options outstanding on the date of death; (ii) a Nonstatutory Stock Option or any right granted thereunder may be transferable pursuant to a qualified domestic relations order as defined in the Code or Title I of the Employee Retirement Income Security Act; and (iii) any Participant, who is a senior executive officer recommended by the Chief Executive Officer and approved by the Administrator may voluntarily transfer any Nonstatutory Stock Option to a Family Member as a gift or through a transfer to an entity in which more than 50% of the voting interests are owned by Family Members (or the Participant) in exchange for an interest in that entity. In the event of any attempt by a Participant to alienate, assign, pledge, hypothecate, or otherwise dispose of an Option or of any right thereunder, except as provided herein, or in the event of the levy of any attachment, execution, or similar process upon the rights or interest hereby conferred, the Corporation at its election may terminate the affected Option by notice to the Participant and the Option shall thereupon become null and void.

     (f)  Termination of Employment .

     Each Option Agreement shall set forth the extent to which the Participant shall have the right to exercise the Option following termination of the Participant’s employment or service with the Corporation and its Affiliates. Such provisions shall be determined in the sole

discretion of the Administrator, need not be uniform among all Options issued pursuant to the Plan, and may reflect distinctions based on the reasons for termination of employment. Unless otherwise provided in Section 3(d) and the Option Agreement, the Administrator may, in its sole discretion, extend the post-termination exercise period with respect to an option (but not beyond the original term of such option).

     (g)  Rights as a Stockholder .

     A Participant or a transferee of a Participant shall have no rights as a stockholder with respect to any Shares covered by his or her Option until the date of issuance of such Shares. Except as provided in Section 16, no adjustment shall be made for dividends, distributions or other rights for which the record date is prior to the date such Shares are issued.

     (h)  Limitation of Incentive Stock Option Awards .

     If and to the extent that the aggregate Fair Market Value (determined as of the date the Option is granted) of the Shares with respect to which any Incentive Stock Options are exercisable for the first time by a Participant during any calendar year under this Plan and all other plans maintained by the Corporation, its parent or its Subsidiaries exceeds $100,000, the Options covering Shares in excess of such amount (taking into account the order in which the Options were granted) shall be treated as Nonstatutory Stock Options.

     (i)  Other Terms and Conditions .

     The Option Agreement may contain such other terms and conditions, including restrictions or conditions on the vesting of the Option or the conditions under which the Option may be forfeited, as may be determined by the Administrator that are consistent with the Plan.

7. STOCK APPRECIATION RIGHTS .

     Stock Appreciation Rights granted to Employees pursuant to the Plan may be granted alone, in addition to, or in conjunction with, Options. Stock Appreciation Rights shall be evidenced by written Stock Appreciation Right Agreements in such form as the Administrator shall determine and shall be subject to the following terms and conditions:

     (a)  Number of Shares .

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