UNDERWRITING AGREEMENT

Exhibit 1.1

McKESSON CORPORATION

$1,000,000,000

5.25% Notes due 2013
5.70% Notes due 2017

UNDERWRITING AGREEMENT

February 28, 2007

Banc of America Securities LLC
Wachovia Capital Markets, LLC

Underwriting Agreement

February 28, 2007

BANC OF AMERICA SECURITIES LLC
WACHOVIA CAPITAL MARKETS, LLC

As Representatives of the several Underwriters

9 West 57th Street
New York, NY 10019

Ladies and Gentlemen:

      Introductory. McKesson Corporation, a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule A (the “Underwriters”), acting severally and not jointly, the respective amounts set forth in such Schedule A of $500,000,000 aggregate principal amount of the Company’s 5.25% Notes due 2013 (the “2013 Notes”) and $500,000,000 aggregate principal amount of the Company’s 5.70% Notes due 2017 (the “2017 Notes” and, together with the 2013 Notes, the “Notes”). Banc of America Securities LLC and Wachovia Capital Markets, LLC have agreed to act as representatives of the several Underwriters (in such capacity, the “Representatives”) in connection with the offering and sale of the Notes.

     The Notes will be issued pursuant to an indenture to be dated as of the Closing Date (the “Base Indenture”), between the Company and The Bank of New York Trust Company, N.A., as trustee (the “Trustee”). Certain terms of the Notes will be established pursuant to an officer’s certificate (the “Officer’s Certificate”) to the Base Indenture (together with the Base Indenture, the “Indenture”). The Notes will be issued in book-entry form in the name of Cede & Co., as nominee of The Depository Trust Company (the “Depositary”), pursuant to a Letter of Representations, to be dated on or before the Closing Date (as defined in Section 2 below) (the “DTC Agreement”), between the Company and the Depositary.

     The Company has prepared and filed with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-3 (File No. 333-124921), which contains a base prospectus (the “Base Prospectus”), to be used in connection with the public offering and sale of debt securities, including the Notes, and other securities of the Company under the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder (collectively, the “Securities Act”), and the offering thereof from time to time in accordance with Rule 415 under the Securities Act. Such registration statement, including the financial statements, exhibits and schedules thereto, in the form in which it became effective under the Securities Act, including any information deemed to be a part thereof at the time of effectiveness pursuant to Rule 430B under the Securities Act, is called the “Registration Statement.” The term “Prospectus” shall mean the final prospectus supplement relating to the Notes, together with the

Base Prospectus, that is first filed pursuant to Rule 424(b) under the Securities Act after the date and time that this Agreement is executed (the “Execution Time”) by the parties hereto. The term “Preliminary Prospectus” shall mean any preliminary prospectus supplement relating to the Notes, together with the Base Prospectus, that is first filed with the Commission pursuant to Rule 424(b) under the Securities Act. Any reference herein to the Registration Statement, the Preliminary Prospectus or the Prospectus shall be deemed to refer to and include the documents that are or are deemed to be incorporated by reference therein pursuant to Item 12 of Form S-3 under the Securities Act prior to 1:00 p.m. (Eastern time) on February 28, 2007 (the “Initial Sale Time”). All references in this Agreement to the Registration Statement, the Preliminary Prospectus, the Prospectus, or any amendments or supplements to any of the foregoing, shall be deemed to be the electronically transmitted copy thereof filed with the Commission pursuant to its Electronic Data Gathering, Analysis and Retrieval System (“EDGAR”).

     All references in this Agreement to financial statements and schedules and other information which is “contained,” “included” or “stated” (or other references of like import) in the Registration Statement, the Prospectus or the Preliminary Prospectus shall be deemed to mean and include all such financial statements and schedules and other information which is or is deemed to be incorporated by reference in the Registration Statement, the Prospectus or the Preliminary Prospectus, as the case may be, prior to the Initial Sale Time; and all references in this Agreement to amendments or supplements to the Registration Statement, the Prospectus or the Preliminary Prospectus shall be deemed to include the filing of any document under the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder (collectively, the “Exchange Act”), which is or is deemed to be incorporated by reference in the Registration Statement, the Prospectus or the Preliminary Prospectus, as the case may be, after the Initial Sale Time.

The Company hereby confirms its agreements with the Underwriters as follows:

      Section 1. Representations and Warranties of the Company

     The Company hereby represents, warrants and covenants to each Underwriter as follows:

     (a)  Compliance with Registration Requirements. The Company meets the requirements for use of Form S-3 under the Securities Act. The Registration Statement has become effective under the Securities Act and no stop order suspending the effectiveness of the Registration Statement has been issued under the Securities Act and no proceedings for that purpose have been instituted or are pending or, to the knowledge of the Company, are contemplated or threatened by the Commission, and any request on the part of the Commission for additional information has been complied with. In addition, the Indenture has been duly qualified under the Trust Indenture Act of 1939, as amended, and the rules and regulations promulgated thereunder (the “Trust Indenture Act”).

     At the respective times the Registration Statement and any post-effective amendments thereto (including the filing with the Commission of the Company’s Annual Report on Form 10-K for the year ended 2006 (the “Annual Report on Form 10-K”)) became effective and as of the date hereof the Registration Statement and any amendments thereto (i) complied and will comply in all material respects with the requirements of the Securities Act and the Trust Indenture Act,

and (ii) did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading. At the date of the Prospectus and at the Closing Date, neither the Prospectus nor any amendments or supplements thereto included or will include an untrue statement of a material fact or omitted or will omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. Notwithstanding the foregoing, the representations and warranties in this subsection shall not apply to statements in or omissions from the Registration Statement or any post-effective amendment or the Prospectus or any amendments or supplements thereto made in reliance upon and in conformity with information furnished to the Company in writing by any of the Underwriters through the Representatives expressly for use therein (it being understood and agreed that the only such information furnished by any Underwriter through the Representatives consists of the information described as such in Section 8 hereof) and to those parts of the Registration Statement that constitute the Statement of Eligibility (Form T-1) under the Trust Indenture Act of the Trustee.

     Each Preliminary Prospectus and the Prospectus, at the time each was filed with the SEC, complied in all material respects with the Securities Act, and the Preliminary Prospectus and the Prospectus delivered to the Underwriters for use in connection with the offering of the Notes will, at the time of such delivery, be identical to any electronically transmitted copies thereof filed with the Commission pursuant to EDGAR, except to the extent permitted by Regulation S-T.

     (b)  Disclosure Package. The term “Disclosure Package” shall mean (i) the Preliminary Prospectus dated February 27, 2007, (ii) the issuer free writing prospectuses as defined in Rule 433 under the Securities Act (each, an “Issuer Free Writing Prospectus”), if any, identified in Schedule B hereto and (iii) any other free writing prospectus that the parties hereto shall hereafter expressly agree in writing to treat as part of the Disclosure Package. As of the Initial Sale Time, the Disclosure Package did not contain any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from the Disclosure Package based upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter through the Representatives consists of the information described as such in Section 8 hereof.

     (c)  Incorporated Documents . The documents incorporated by reference in the Registration Statement , the Disclosure Package and the Prospectus, when they became effective or were filed with the Commission, as the case may be, conformed in all material respects to the requirements of the Securities Act or the Exchange Act, as applicable, and none of such documents contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading; and any further documents so filed and incorporated by reference in the Registration Statement, the Disclosure Package and the Prospectus or any further amendment or supplement thereto, when such documents become effective or are filed with the Commission, as the case may be, will conform in all material

respects to the requirements of the Securities Act or the Exchange Act, as applicable, and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading.

     (d)  Company is a Well-Known Seasoned Issuer . At the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Securities Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus), at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c) under the Securities Act) made any offer relating to the Notes in reliance on the exemption of Rule 163 under the Securities Act, and as of the Execution Time, the Company was and is a “well known seasoned issuer” as defined in Rule 405 under the Securities Act.

     (e)  Company is not an Ineligible Issuer . (i) At the time of filing the Registration Statement and (ii) as of the Execution Time (with such date being used as the determination date for purposes of this clause (ii)), the Company was not and is not an “ineligible issuer” (as defined in Rule 405 under the Securities Act), without taking account of any determination by the Commission pursuant to Rule 405 under the Securities Act that it is not necessary that the Company be considered an ineligible issuer.

     (f)  Issuer Free Writing Prospectuses . Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the offering of Notes under this Agreement or until any earlier date that the Company notified or notifies the Representatives as described in the next sentence, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information contained in the Registration Statement, the Disclosure Package or the Prospectus, including any document incorporated or deemed to be incorporated by reference therein that has not been superseded or modified. If at any time following issuance of an Issuer Free Writing Prospectus there occurred or occurs an event or development as a result of which such Issuer Free Writing Prospectus conflicted or would conflict with the information contained in the Registration Statement, the Preliminary Prospectus or the Prospectus the Company has promptly notified or will promptly notify the Representatives and has promptly amended or supplemented or will promptly amend or supplement, at its own expense, such Issuer Free Writing Prospectus to eliminate or correct such conflict. The foregoing two sentences do not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter through the Representatives consists of the information described as such in Section 8 hereof.

     (g)  Distribution of Offering Material By the Company. The Company has not distributed and will not distribute, prior to the later of the Closing Date and the completion of the Underwriters’ distribution of the Notes, any offering material in connection with the offering and sale of the Notes other than the Preliminary Prospectus, the Prospectus, any Permitted Free Writing Prospectus (as defined below) or the Registration Statement.

     (h)  No Applicable Registration or Other Similar Rights. There are no persons with registration or other similar rights to have any equity or debt securities registered for sale under the Registration Statement or included in the offering contemplated by this Agreement, except for such rights as have been duly waived.

     (i)  The Underwriting Agreement. This Agreement has been duly authorized, executed and delivered by the Company.

     (j)  Authorization of the Indenture . The Indenture has been duly qualified under the Trust Indenture Act and has been duly authorized by the Company and, when executed and delivered by the Company and assuming the due authorization, execution and delivery by the Trustee, will constitute a valid and binding agreement of the Company, enforceable against the Company in accordance with its terms, except as the enforcement thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium or other similar laws relating to or affecting the rights and remedies of creditors or by general equitable principles.

     (k)  Authorization of the Notes. The Notes to be purchased by the Underwriters from the Company are in the form contemplated by the Indenture, have been duly authorized for issuance and sale pursuant to this Agreement and the Indenture and, at the Closing Date, will have been duly executed by the Company and, when authenticated in the manner provided for in the Indenture and delivered against payment of the purchase price therefor, will constitute valid and binding obligations of the Company, enforceable in accordance with their terms, except as the enforcement thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium or other similar laws relating to or affecting the rights and remedies of creditors or by general equitable principles, and will be entitled to the benefits of the Indenture.

     (l)  Description of the Notes and the Indenture. The Notes and the Indenture conform in all material respects to the descriptions thereof contained in the Disclosure Package and the Prospectus.

     (m)  No Material Adverse Change . Except as otherwise disclosed in the Disclosure Package, subsequent to the respective dates as of which information is given in the Disclosure Package, there has been no material adverse change, or any development that could reasonably be expected to result in a material adverse change, in the condition, financial or otherwise, or in the earnings, management, business, properties, results of operations or prospects, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries, considered as one entity (any such change is called a “Material Adverse Change”).

     (n)  Independent Accountants. Deloitte & Touche LLP, who have expressed their opinion with respect to the Company’s audited financial statements for the fiscal years ended 2004, 2005 and 2006 incorporated by reference in the Registration Statement, the Preliminary Prospectus and the Prospectus, are independent public accountants with respect to the Company as required by the Securities Act and the Exchange Act and are a registered public accounting firm with the Public Company Accounting Oversight Board.

     (o)  Preparation of the Financial Statements. The financial statements together with the related notes thereto incorporated by reference in the Registration Statement, the Preliminary Prospectus and the Prospectus present fairly in all material respects the consolidated financial position of the Company and its subsidiaries as of and at the dates indicated and the results of their operations and cash flows for the periods specified. Such financial statements comply as to form with the accounting requirements of the Securities Act and have been prepared in conformity with generally accepted accounting principles as applied in the United States applied on a consistent basis throughout the periods involved, except as may be expressly stated in the related notes thereto.

     (p)  Incorporation and Good Standing of the Company and its Significant Subsidiary. The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Delaware and has corporate power and authority to own or lease, as the case may be, and operate its properties and to conduct its business as described in the Disclosure Package and the Prospectus and to enter into and perform its obligations under this Agreement. The Company is duly qualified as a foreign corporation to transact business and is in good standing in each jurisdiction in which such qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except for such jurisdictions where the failure to so qualify or to be in good standing would not, individually or in the aggregate, have a material adverse effect on the condition, financial or otherwise, earnings, management, business, properties, results of operations or prospects of the Company and its subsidiaries, considered as one entity (a “Material Adverse Effect”). McKesson Information Solutions Holdings Limited, an Ireland corporation, is the Company’s sole significant subsidiary, as defined by Rule 1-02(w) of Regulation S-X under the Securities Act (the “Significant Subsidiary”), and has been duly incorporated and is validly existing as a corporation under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own its property and to conduct its business as presently conducted.

     (q)  Non-Contravention of Existing Instruments; No Further Authorizations or Approvals Required. The execution and delivery by the Company of this Agreement, the Indenture and the Notes (collectively, the “Operative Instruments”), and the consummation by the Company of the transactions contemplated thereby, including the issuance and sale of the Notes, (A) will not violate or conflict with or result in any contravention of any provision of the General Corporation Law of the State of Delaware (the “DGCL”), or (B) conflict with the charter or by-laws of the Company, or (C) constitute a violation of, or a breach or default under the laws of any agreement, contract, bond, indenture or other instrument binding upon the Company or any of its subsidiaries that is material to the Company and its subsidiaries, taken as a whole, (D) violate or conflict with, or result in any contravention of, any judgment, order or decree of any governmental body, agency or court having jurisdiction over the Company or any subsidiary of the Company, except for a violation, conflict or contravention which would not, individually or in the aggregate, have a Material Adverse Effect, (E) do not and will not result in the imposition of any lien, charge or encumbrance upon any assets of the Company or any of its subsidiaries, pursuant to the terms of any agreement or instrument to which the Company or any of its subsidiaries is a party or by which any of them or any of their respective properties is bound, except for any liens, charges or encumbrances which would not, individually or in the aggregate, have a Material Adverse Effect, and (F) do not require any consent, approval, authorization or order of, or qualification with, any governmental body or agency, except such as may be required

by the securities or Blue Sky laws of the various states, the Securities Act, the Exchange Act, the Trust Indenture Act and the securities laws of any jurisdiction outside the United States in which the Notes are offered.

     (r)  No Material Actions or Proceedings. There are no legal or governmental proceedings pending or, to the best of the Company’s knowledge, threatened to which the Company or any of its subsidiaries is a party or to which any of the properties of the Company or any of its subsidiaries is subject (i) which are required to be described in the documents incorporated by reference in the Registration Statement, the Disclosure Package or the Prospectus and are not so described or (ii) which could reasonably be expected to result in a Material Adverse Change, or materially affect the power or ability of the Company to perform its obligations under the Operative Instruments or to consummate any of the transactions contemplated by the Disclosure Package and the Prospectus or the Operative Instruments. There are no contracts or other documents that are required to be described in the documents incorporated by reference in the Registration Statement, the Disclosure Package or Prospectus or to be filed as exhibits to the Registration Statement that are not described or filed as required.

     (s)  Intellectual Property Rights. Except as set forth in the Disclosure Package and the Prospectus, to the Company’s knowledge, the Company or its subsidiaries own or possess a valid right to use all patents, trademarks, service marks, trade names, copyrights, patentable inventions, trade secrets, know-how and other intellectual property (collectively, the “Intellectual Property”) used by the Company or its subsidiaries in, and material to, the conduct of the Company’s or its subsidiaries’ business as now conducted or as proposed in the Disclosure Package and the Prospectus to be conducted, except as would not, individually or in the aggregate, result in a Material Adverse Change or adversely affect the consummation of the transactions contemplated by this Agreement.

     (t)  All Necessary Permits, etc. Each of the Company and its subsidiaries has all necessary consents, authorizations, approvals, orders, certificates and permits (collectively, “Permits”) of and from, and has made all declarations and filings with, all federal, state, provincial, local and other governmental authorities, all self-regulatory organizations and all courts and other tribunals, to own, lease, license and use its properties and assets and to conduct its business in the manner described in the Disclosure Package and the Prospectus, except to the extent that the failure to obtain or file could not reasonably be expected to have a Material Adverse Effect. Neither the Company nor any of its subsidiaries has received any notice of proceedings relating to the revocation or modification of any such Permits which, individually or in the aggregate, if the subject of an unfavorable decision, ruling or finding, could reasonably be expected to have a Material Adverse Effect.

     (u)  Compliance with Environmental Laws. The Company and its subsidiaries (i) are in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or regulated wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) are in compliance with all terms and conditions of any such permit, license or approval, except where such noncompliance with Environmental Laws, failure to receive required permits, licenses or other approvals or

failure to comply with the terms and conditions of such permits, licenses or approvals would not, individually or in the aggregate, have a Material Adverse Effect.

     (v)  Environmental Costs . There are no costs or liabilities associated with Environmental Laws (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties) which would, individually or in the aggregate, have a Material Adverse Effect, except as otherwise disclosed or incorporated by reference in the Disclosure Package.

     (w)  Tax Law Compliance. The Company and its subsidiaries have filed all necessary federal, state, local and foreign income and franchise tax returns in a timely manner and have paid all taxes required to be paid by any of them and, if due and payable, any related or similar assessment, fine or penalty levied against any of them, except for any taxes, assessments, fines or penalties as may be being contested in good faith and by appropriate proceedings, except where a default to make such filings or payments would not result in a Material Adverse Change.

     (x)  Company Not an “Investment Company. The Company is not, and after receipt of payment for the Notes and the application of the proceeds thereof as contemplated under the caption “Use of Proceeds” in the Preliminary Prospectus and the Prospectus will not be an “investment company” within the meaning of the Investment Company Act of 1940, as amended (the “Investment Company Act”).

     (y)  No Price Stabilization or Manipulation. The Company has not taken and will not take, directly or indirectly, any action designed to or that would be reasonably expected to cause or result in stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Notes.

     (z)  Sarbanes-Oxley Compliance . The Company has complied in all material respects with the applicable provisions of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith.

     (aa)  Controls. The Company maintains a system of internal control over financial reporting (as such term is defined in Rule 13a-15(f) under the Exchange Act) that complies with the requirements of the Exchange Act and has been designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. The internal control over financial reporting of the Company is effective.

     Any certificate signed by an officer of the Company and delivered to the Representatives or to counsel for the Underwriters shall be deemed to be a representation and warranty by the Company to each Underwriter as to the matters set forth therein.

      Section 2. Purchase, Sale and Delivery of the Shares.

     (a)  The Notes. The Company agrees to issue and sell to the several Underwriters, severally and not jointly, all of the Notes upon the terms herein set forth. On the basis of the representations, warranties and agreements herein contained, and upon the terms but subject to

the conditions herein set forth, each Underwriter agrees, severally and not jointly, to purchase from the Company the aggregate principal amount of Notes set forth opposite its name on Schedule A, plus any additional principal amount of Notes that such Underwriter may become obligated to purchase pursuant to Section 10 of this Agreement, at a purchase price of 98.955% of the principal amount of the 2013 Notes and 99.185% of the principal amount of the 2017 Notes, payable on the Closing Date.

     (b)  The Closing Date. Delivery of certificates for the Notes in global form to be purchased by the Underwriters and payment therefor shall be made at the offices of Mayer, Brown, Rowe & Maw LLP, 71 South Wacker Drive, Chicago, IL 60606 (or such other place as may be agreed to by the Company and the Representatives) at 9:00 a.m., New York City time, on March 5, 2007, or such other time and date as the Underwriters and the Company shall mutually agree (the time and date of such closing are called the “Closing Date”).

     (c)  Public Offering of the Notes. The Representatives hereby advise the Company that the Underwriters intend to offer for sale to the public, as described in the Disclosure Package and the Prospectus, their respective portions of the Notes as soon after the Execution Time as the Representatives, in their sole judgment, have determined is advisable and practicable.

     (d)  Payment for the Notes. Payment for the Notes shall be made at the Closing Date by wire transfer of immediately available funds to the order of the Company.

     It is understood that the Representatives have been authorized, for their own accounts and for the accounts of the several Underwriters, to accept delivery of and receipt for, and make payment of the purchase price for, the Notes that the Underwriters have agreed to purchase. The Representatives may (but shall not be obligated to) make payment for any Notes to be purchased by any Underwriter whose funds shall not have been received by the Representatives by the Closing Date for the account of such Underwriter, but any such payment shall not relieve such Underwriter from any of its obligations under this Agreement.

     (e)  Delivery of the Notes. The Company shall deliver, or cause to be delivered, to the Representatives for the accounts of the several Underwriters the Notes at the Closing Date, against the irrevocable release of a wire transfer of immediately available funds for the amount of the purchase price therefor. The Notes shall be issued in book-entry only form and shall be represented by one or more global certificates in such denominations and registered in such names and denominations as the Representatives shall have requested at least two full business days prior to the Closing Date and shall be made available for inspection on the business day preceding the Closing Date at a location in New York City, as the Representatives may designate. Time shall be of the essence, and delivery at the time and place specified in this Agreement is a further condition to the obligations of the Underwriters.

      Section 3. Covenants of the Company.

     The Company covenants and agrees with each Underwriter as follows:

     (a)  Compliance with Securities Regulations and Commission Requests. The Company will promptly notify the Representatives, and confirm the notice in writing, of (i) the effectiveness during the Prospectus Delivery Period (as defined below) of any post-effective

amendment to the Registration Statement or the filing of any supplement or amendment to the Preliminary Prospectus or the Prospectus, (ii) the receipt of any comments from the Commission during the Prospectus Delivery Period, (iii)&