Exhibit 5.1

Altria Group, Inc.

Philip Morris USA Inc.

6601 West Broad Street

Richmond, Virginia 23230

Re: Legality of Securities Issued under Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as special counsel to Altria Group, Inc., a Virginia corporation (the “Company”), and Philip Morris USA Inc., a Virginia corporation and a wholly-owned subsidiary of the Company (the “Guarantor”), in connection with (1) the registration of an indeterminate amount of debt securities of the Company (the “Debt Securities”), guarantees of the Debt Securities by the Guarantor and warrants to purchase Debt Securities, as set forth in the Registration Statement on Form S-3 (Registration No. 333-155009) (the “Registration Statement”) filed by the Company and the Guarantor on November 4, 2008 with the Securities and Exchange Commission (the “Commission”) pursuant to the Securities Act of 1933, as amended (the “Act”), and (2) the Company’s offering and sale of $1,500,000,000 aggregate principal amount of its 4.750% Notes due 2021 (the “Notes”). The Notes are fully and unconditionally guaranteed as to payment of principal, premium, if any, and interest by the Guarantor (the “Guarantee”).

The Notes are being offered and sold as described in the prospectus, dated November 4, 2008, contained in the Registration Statement, and the prospectus supplement thereto, dated May 2, 2011 (collectively, the “Prospectus”). The Notes have been issued pursuant to an indenture (the “Indenture”), dated as of November 4, 2008, among the Company, the Guarantor and Deutsche Bank Trust Company Americas, as trustee (the “Trustee”). The Guarantee has been issued pursuant to the Indenture as evidenced by a guarantee agreement (the “Guarantee Agreement”) made by the Guarantor in favor of the Trustee.

This opinion is being furnished in accordance with the requirements of Item 16 of Form S-3 and Item 601(b)(5)(i) of Regulation S-K.

We have examined originals or reproductions or certified copies of such records of the Company and the Guarantor, certificates of officers of the Company and the Guarantor and of

ATLANTA    AUSTIN    BANGKOK    BEIJING     BRUSSELS    CHARLOTTE    DALLAS    HOUSTON    LONDON    LOS ANGELES

MCLEAN    MIAMI    NEW YORK    NORFOLK    RALEIGH    RICHMOND    SAN FRANCISCO    WASHINGTON

www.hunton.com

Altria Group, Inc.

Philip Morris USA Inc.

May 5, 2011

Page 2

public officials and such other documents as we have deemed necessary for the purpose of rendering this opinion, including, among other things:

For purposes of the opinions expressed below, we have assumed: (i) the authenticity of all documents submitted to us as originals; (ii) the conformity to the originals of all documents submitted to us as certified photostatic or electronic copies and the authenticity of the originals of such documents; (iii) the legal capacity of natural persons; (iv) the genuineness of all signatures; and (v) the due authorization, execution and delivery of all documents by all parties and the validity, binding effect and enforceability thereof (other than the due authorization, execution and delivery of documents by the Company and the Guarantor and the validity, binding effect and enforceability thereof upon the Company and the Guarantor).

Altria Group, Inc.

Philip Morris USA Inc.

May 5, 2011

Page 3

We do not purport to express an opinion on any laws other than those of the Commonwealth of Virginia, the State of New York and the federal laws of the United States of America.

Based upon the foregoing and subject to the qualifications set forth below, we are of the opinion that:

1. The Notes are valid, binding and enforceable obligations of the Company, entitled to the benefits of the Indenture.

2. The Guarantee is a valid, binding and enforceable obligation of the Guarantor.

The opinions set forth above are subject to the qualification that the validity and enforcement of the Company’s obligations under the Indenture and the Notes and the Guarantor’s obligations under the Guarantee and the underlying Guarantee Agreement may be subject to (i) the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium or other laws now or hereafter in effect relating to or affecting creditors’ rights generally, (ii) general principles of equity (whether considered in a proceeding at law or in equity) and (iii) concepts of materiality, unconscionability, reasonableness, impracticability or impossibility of performance and any implied covenant of good faith and fair dealing.

We hereby consent to (a) the filing of this opinion with the Commission as an exhibit to the Company’s Current Report on Form 8-K filed on the date hereof, (b) the incorporation by reference of this opinion into the Registration Statement and (c) the reference to our firm under the heading “Legal Matters” in the Registration Statement and the Prospectus. By giving such consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission promulgated thereunder.

Altria Group, Inc.

Philip Morris USA Inc.

May 5, 2011

Page 4

This opinion is limited to the matters stated in this letter, and no opinions may be implied or inferred beyond the matters expressly stated in this letter. This opinion is given as of the date hereof and we assume no obligation to advise you after the date hereof of facts or circumstances that come to our attention or changes in the law, including judicial or administrative interpretations thereof, that occur which could affect the opinions contained herein.