Exhibit 5.1

[Citi Logo]   Citigroup Inc. 399 Park Avenue New York, New York  10022

February 25, 2008

Citibank (South Dakota), National Association

701 East 60th Street, North

Sioux Falls, South Dakota 57117

Ladies and Gentlemen:

I am the General Counsel, Finance and Capital Markets of Citigroup Inc. and, in such capacity, I have acted as counsel to Citibank (South Dakota), National Association in connection with the issuance and sale of $750,000,000 aggregate principal amount of Citiseries Floating Rate Class 2008-A2 Notes of January 2018 (Legal Maturity Date January 2020) (the "Notes") by Citibank Credit Card Issuance Trust (the "Issuance Trust").  The Notes will be issued pursuant to an Indenture dated as of September 26, 2000 between the Issuance Trust and Deutsche Bank Trust Company Americas (formerly Bankers Trust Company), as Trustee, as amended by Amendment No. 1 thereto dated as of November 14, 2001 and an Issuer Certificate, dated as of February 25, 2008, relating to the Notes (the "Terms Document" and together, the "Indenture"). Capitalized terms used but not otherwise defined herein shall have the meanings ascribed to them in or pursuant to the Indenture.

I, or attorneys under my supervision, have examined and relied upon the following: signed copies of the Indenture and the Registration Statement on Form S-3 (Registration No. 333-145220), as amended (the "Registration Statement"), for the registration of the Collateral Certificate and the Notes under the Securities Act of 1933, as amended (the "Act"); the prospectus dated January 23, 2008 and prospectus supplement dated February 15, 2008 relating to the Notes (together, the "Prospectus"); a specimen of the Notes, and originals, or copies certified or otherwise identified to my satisfaction, of such corporate records, certificates or documents as I have deemed appropriate as a basis for the opinion expressed below.  In such examination, I (or such persons) have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to me (or such persons) as originals, the conformity to original documents of all documents submitted to me (or such persons) as certified or photostatic copies and the authenticity of the originals of such copies.

Based upon and subject to the foregoing, I am of the opinion that when the Notes have been duly executed, authenticated and delivered in accordance with the Indenture, and sold in the manner described in the Prospectus, the Notes will be legally issued, fully paid, non-assessable and binding obligations of the Issuance Trust, and the holders of the Notes will be entitled to the benefits of the Indenture.

Citibank (South Dakota), National Association

Citiseries Class 2008-A2

February 25, 2008

Page 2

The foregoing opinion is subject to applicable bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws affecting creditors' rights generally from time to time in effect and subject to general principles of equity, regardless of whether such is considered in a proceeding in equity or at law.

I am admitted to the practice of law only in the State of New York and my opinion is limited to matters governed by the laws of the State of New York and Federal laws of the United States of America.

I consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to a Current Report on Form 8-K for incorporation into the Registration Statement and to the reference to my name in the Prospectus constituting a part of such Registration Statement under the heading "Legal Matters". In giving such consent, I do not thereby admit that I come within the category of persons whose consent is required under Section 7 of the Act, or the rules and regulations of the Securities and Exchange Commission thereunder.

Very truly yours,

/s/ Michael S. Zuckert

Michael S. Zuckert