EXHIBIT 5.02

            [Letterhead of Skadden, Arps, Slate, Meagher & Flom LLP]


                                                   September 5, 2006


Citigroup Inc.
399 Park Avenue
New York, NY  10043

Citigroup Capital XV
Citigroup Capital XVI
Citigroup Capital XVII
Citigroup Capital XVIII

c/o Citigroup Inc.
399 Park Avenue
New York, NY 10043

      Re:   Post-Effective Amendment to Registration Statement on Form S-3

Ladies and Gentlemen:

      We have acted as special counsel to (1) Citigroup Capital XV, Citigroup
Capital XVI, Citigroup Capital XVII and Citigroup Capital XVIII (the "Citigroup
Trusts," each a statutory business trust created under the laws of the State of
Delaware), and (2) Citigroup Inc. (the "Company"), a corporation organized under
the laws of the State of Delaware, in connection with the preparation of a
Post-Effective Amendment to the Registration Statement on Form S-3 (File No.
333-135163) (the "Registration Statement"), filed by the Company and the
Citigroup Trusts with the Securities and Exchange Commission (the "Commission")
on September 5, 2006 under the Securities Act of 1933, as amended (the "Act").
The Registration Statement relates to, among other things, the issuance and sale
from time to time pursuant to Rule 415 of the General Rules and Regulations
promulgated under the Act, of the following securities: (i) enhanced capital
securities (the "Enhanced Capital Securities") of each of the Citigroup Trusts
and (ii) unsecured junior subordinated debt securities related to the Enhanced
Capital Securities (the "Junior Subordinated Debt Securities") which are to be
issued pursuant to an Indenture (the "Enhanced Capital Securities Indenture") to
be entered into between

c/o Citigroup Inc.
September 5, 2006
Page 2



the Company and the JPMorgan Chase Bank, as debt trustee (the "Debt Trustee").
The Enhanced Capital Securities of each Citigroup Trust are to be issued
pursuant to the Amended and Restated Declaration of Trust of such Citigroup
Trust (each, a "Declaration" and, collectively, the "Declarations"), each such
Declaration being among the Company, as sponsor and as the issuer of the Junior
Subordinated Debt Securities to be held by the Property Trustee (as defined
below) of such Citigroup Trust, Chase Bank USA, National Association, as
Delaware trustee (the "Delaware Trustee"), JPMorgan Chase Bank, as property
trustee (the "Property Trustee"), and John Gerspach, Sallie Krawcheck and Saul
Rosen, as regular trustees (together, the "Regular Trustees").

      This opinion is being delivered in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Act. Capitalized terms used but not
otherwise defined herein have the meanings ascribed to them in the Registration
Statement.

      In connection with this opinion, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of (i) the Registration
Statement, (ii) the certificates of trust of each of the Citigroup Trusts, as
filed with the Secretary of State of the State of Delaware on July 19, 2006
(collectively, the "Certificates of Trust"); (iii) the form of the Declaration
of each of the Citigroup Trusts (including the form of the designations of the
terms of the Enhanced Capital Securities of each of the Citigroup Trusts annexed
thereto); (iv) the form of the Enhanced Capital Securities of each of the
Citigroup Trusts; (v) the form of the enhanced capital securities guarantee
agreement (the "Enhanced Capital Securities Guarantee"), to be entered into by
the Company and JPMorgan Chase Bank, as guarantee trustee (the "Enhanced Capital
Securities Guarantee Trustee"); (vi) the form of the Junior Subordinated Debt
Securities; (vii) the form of the Enhanced Capital Securities Indenture (viii)
the Restated Certificate of Incorporation of the Company, as certified by the
Secretary of State of the State of Delaware (the "Certificate of
Incorporation"); (ix) the By-Laws of the Company, as amended, as certified by an
Assistant Secretary of the Company (the "By-Laws"); and (x) drafts of certain
resolutions of the Board of Directors of the Company (the "Draft Resolutions")
relating to the issuance and sale of the Offered Enhanced Capital Securities
Debt Securities (as defined below) and the Enhanced Capital Securities Guarantee
and related matters. We have also examined originals or copies, certified or
otherwise identified to our satisfaction, of such other documents, certificates
and records as we have deemed necessary or appropriate as a basis for the
opinions set forth herein.

      In our examination, we have assumed the legal capacity of all natural
persons, the genuineness of all signatures, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified or photostatic copies and the
authenticity of the originals of such copies. In making our examination of
executed documents or documents to be executed, we

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September 5, 2006
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have assumed that the parties thereto, other than the Company and the Citigroup
Trusts, had or will have the power, corporate, trust or other, to enter into and
perform all obligations thereunder and have also assumed the due authorization
by all requisite action, corporate or other, and execution and delivery by such
parties of such documents and that such documents constitute valid and binding
obligations of such parties. In addition, we have assumed that the Enhanced
Capital Securities Indenture, the Declaration of each Citigroup Trust, the
Enhanced Capital Securities of each Citigroup Trust, the Enhanced Capital
Securities Guarantee and the Junior Subordinated Debt Securities will be
executed in substantially the form reviewed by us and that the terms of the
Offered Enhanced Capital Securities (as defined below) and the Offered Enhanced
Capital Securities Debt Securities, will have been established so as not to
violate, conflict with or constitute a default under (i) any agreement or
instrument to which the Company or any of the Citigroup Trusts or their
respective property is subject, (ii) any law, rule, or regulation to which the
Company or any of the Citigroup Trusts is subject, (iii) any judicial or
administrative order or decree of any governmental authority or (iv) any
consent, approval, license, authorization or validation of, or filing, recording
or registration with any governmental authority. As to any facts material to the
opinions expressed herein that were not independently established or verified,
we have relied upon oral or written statements and representations of officers,
trustees and other representatives of the Company, the Citigroup Trusts and
others.

      We do not express any opinion as to any laws other than Delaware corporate
law and the laws of the State of New York. Insofar as the opinions expressed
herein relate to matters governed by laws other than those set forth in the
preceding sentence, we have assumed, without having made any independent
investigation, that such laws do not affect any of the opinions set forth
herein. The opinions expressed herein are based on laws in effect on the date
hereof, which laws are subject to change with possible retroactive effect.

      Based on and subject to the foregoing and to the other qualifications and
limitations set forth herein, we are of the opinion that:

      1. With respect to the Enhanced Capital Securities of each Citigroup Trust
      to be offered pursuant to the Registration Statement (the "Offered
      Enhanced Capital Securities"), when (i) the Declaration of such Citigroup
      Trust has been duly executed and delivered by the parties thereto; (ii)
      the terms of the Offered Enhanced Capital Securities have been established
      in accordance with the Declaration; (iii) the Offered Enhanced Capital
      Securities have been issued, executed and authenticated in accordance with
      the Declaration and delivered and paid for in the manner contemplated in
      the Registration Statement or any prospectus relating thereto; and (iv) if
      the Offered Enhanced Capital Securities are to be sold pursuant to a firm

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September 5, 2006
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      commitment underwritten offering, the underwriting agreement with respect
      to the Offered Enhanced Capital Securities has been duly authorized,
      executed and delivered by the applicable Citigroup Trust and the other
      parties thereto, (1) the Offered Enhanced Capital Securities will be duly
      authorized for issuance and will be validly issued, fully paid and
      nonassessable, representing undivided beneficial interests in the assets
      of such Citigroup Trust and (2) the holders of the Offered Enhanced
      Capital Securities will be entitled to the same limitation of personal
      liability extended to stockholders of private corporations for profit
      organized under the DGCL. We bring to your attention, however, that the
      holders of the Offered Enhanced Capital Securities may be obligated,
      pursuant to the Declaration of such Citigroup Trust, to (i) provide
      indemnity and/or security in connection with, and pay taxes or
      governmental charges arising from, transfers of Offered Enhanced Capital
      Securities and (ii) provide security and indemnity in connection with the
      requests of, or directions to, the Property Trustee of such Citigroup
      Trust to exercise its rights and powers under the Declaration of such
      Citigroup Trust.

      2. With respect to the Enhanced Capital Securities Guarantee, when (i) the
      Draft Resolutions have been adopted by the Board of Directors of the
      Company; (ii) the Declaration of such Citigroup Trust is duly executed and
      delivered by the parties thereto; (iii) the terms of the Offered Enhanced
      Capital Securities have been established in accordance with the
      Declaration; (iv) the Offered Enhanced Capital Securities have been issued
      and executed in accordance with the Declaration and paid for in the manner
      contemplated in the Registration Statement or any prospectus relating
      thereto; and (v) if the Offered Enhanced Capital Securities are to be sold
      pursuant to a firm commitment underwritten offering, the underwriting
      agreement with respect to the Offered Enhanced Capital Securities has been
      duly authorized, executed and delivered by the applicable Citigroup Trust
      and the other parties thereto, the Enhanced Capital Securities Guarantee,
      when duly executed and delivered by the parties thereto, will be a valid
      and binding agreement of the Company, enforceable against the Company in
      accordance with its terms, except to the extent that (a) enforcement
      thereof may be limited by (i) bankruptcy, insolvency, reorganization,
      moratorium, or other similar laws now or hereafter in effect relating to
      creditors' rights generally and (ii) general principles of equity
      (regardless of whether enforceability is considered in a proceeding at law
      or in equity) and (b) rights to indemnity and contribution thereunder may
      be limited by applicable law or the public policy underlying such law.

      3. With respect to any series of Junior Subordinated Debt Securities (the
      "Offered Enhanced Capital Securities Debt Securities"), when (i) the Draft

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September 5, 2006
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      Resolutions have been adopted by the Board of Directors of the Company;
      (ii) the Board of Directors, including any appropriate committee appointed
      thereby, and appropriate officers of the Company have taken all necessary
      corporate action to approve the issuance and terms of the Offered Enhanced
      Capital Securities Debt Securities and related matters; (iii) the Enhanced
      Capital Securities Indenture has been duly executed and delivered by the
      parties thereto; (iv) the terms of the Offered Enhanced Capital Securities
      Debt Securities have been established in conformity with the Enhanced
      Capital Securities Indenture; (v) the Offered Enhanced Capital Securities
      Debt Securities are duly executed, delivered, authenticated and issued in
      accordance with the Enhanced Capital Securities Indenture and delivered
      and paid for in the manner contemplated in the Registration Statement or
      any prospectus relating thereto; and (vi) if the Offered Enhanced Capital
      Securities Debt Securities are to be sold pursuant to a firm commitment
      underwritten offering, the underwriting agreement with respect to the
      Offered Enhanced Capital Securities Debt Securities has been duly
      authorized, executed and delivered by the parties thereto, the Offered
      Enhanced Capital Securities Debt Securities will be valid and binding
      obligations of the Company, entitled to the benefits of the Enhanced
      Capital Securities Indenture and enforceable against the Company in
      accordance with their terms, except to the extent that enforcement thereof
      may be limited by (i) bankruptcy, insolvency, fraudulent conveyance,
      reorganization, moratorium, or other similar laws now or hereafter in
      effect relating to creditors' rights generally and (ii) general principles
      of equity (regardless of whether enforceability is considered in a
      proceeding at law or in equity).

      We note that Section 13.5 of the Enhanced Capital Securities Indenture
provides that, under certain circumstances, the Company will be obligated to use
its commercially reasonable efforts to sell shares of its common stock and to
apply the proceeds from such sale to pay interest on the Junior Subordinated
Debt Securities that was deferred in accordance with Section 13.1 of the
Enhanced Capital Securities Indenture, and that the Company shall be deemed not
to have used its commercially reasonable efforts if it determines not to effect
such sale solely due to pricing considerations. Because the DGCL reserves to the
Board of Directors the exclusive authority to issue stock and to determine the
price at which such stock is to be issued and, since the Board of Directors has
not yet approved the issuance of such shares of common stock or determined the
per share price thereof, we are not rendering any opinion as to the
authorization, issuance or validity of the common stock issuable pursuant to
Section 13.5 of the Enhanced Capital Securities Indenture; in addition, for
purposes of the opinions set forth below, we have assumed that the Board of
Directors will approve such issuance.

c/o Citigroup Inc.
September 5, 2006
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      We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement. We also hereby consent to the use of our
name under the heading "Legal Matters" in each of the two prospectuses which
forms a part of the Registration Statement. In giving this consent, we do not
thereby 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. This opinion is expressed as of the date
hereof unless otherwise expressly stated, and we disclaim any undertaking to
advise you of any subsequent changes in the facts stated or assumed herein or of
any subsequent changes in applicable law.

                                    Very truly yours,

                                    /s/ Skadden, Arps, Slate, Meagher & Flom LLP