FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * OWEN MARC E   2. Issuer Name and Ticker or Trading Symbol MCKESSON CORP [MCK] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) EVP, Corp.Strategy & Bus. Dev. (Last) (First) (Middle) ONE POST STREET 3. Date of Earliest Transaction (Month/Day/Year) 05/18/2010 (Street) SAN FRANCISCO, CA 94104 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 05/18/2010   M   5,000 (2) A $ 39.81 9,114.0475 (1) D   Common Stock 05/18/2010   M   40,000 (2) A $ 45.02 49,114.0475 (1) D   Common Stock 05/18/2010   S   45,000 (2) D $ 70 4,114.0475 (1) D   Common Stock               1,410.6575 I By Profit-Sharing Investment Plan

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Employee Stock Option (Right-to-buy)

$ 39.81

05/18/2010

M

5,000

(3)

10/25/2011

Common Stock

5,000

$ 0

0

D

Employee Stock Option (Right-to-buy)

$ 45.02

05/18/2010

M

40,000

(4)

07/27/2012

Common Stock

40,000

$ 0

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
OWEN MARC E ONE POST STREET SAN FRANCISCO, CA 94104			EVP, Corp.Strategy & Bus. Dev.

Signatures

Donna Spinola, Attorney-in-fact		05/19/2010
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Includes 4,114.0475 shares purchased under the issuer's ESPP.
(2)	Option exercise and sale pursuant to a previously adopted plan dated 03/13/2009, intended to comply with Rule 10b5-1(c).
(3)	This option was granted on 10/26/2001 and vest as follows: 50% on 10/26/2003 and 50% on 1/27/2004.
(4)	This option was granted on 7/27/2005 and vests 100% on 3/31/2006.

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