Exhibit 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

     We consent to the incorporation by reference in McKesson Corporation Registration Statements No. 033-86536, 333-00611, 333-02871, 333-21931, 333-30104, 333-30216, 333-30218, 333-30220, 333-30222, 333-20224, 333-30226, 333-32643, 333-32645, 333-43101, 333-43079, 333-48337, 333-43068, 333-48339, 333-48859, 333-50261, 333-70501, 333-71917, 333-85965, 333-39952, 333-39954, 333-62870, 333-67378, 333-67380, 333-84806, 333-101210, 333-127877 and 333-140422 on Form S-8, Registration Statements No. 333-26103, and Amendment No. 1 thereto, 333-85973, and Amendment Nos. 1 and 2 thereto, and 333-124921 on Form S-3, and Registration Statement No. 333-56623, and Amendment No. 1 thereto, on Form S-4 of our report dated May 9, 2007 (which report expresses an unqualified opinion and includes an explanatory paragraph relating to the adoption of two new accounting standards), relating to the consolidated financial statements and consolidated financial statement schedule of the Company, and management’s report on the effectiveness of internal control over financial reporting, appearing in this Annual Report on Form 10-K of McKesson Corporation for the fiscal year ended March 31, 2007.

/s/ Deloitte & Touche LLP
San Francisco, California
May 9, 2007