Exhibit 8.3

                                [Letterhead of]

                            CRAVATH, SWAINE & MOORE
                               [New York Office]



                                                                 August 30, 2000


                              BANK ONE Capital III
                              --------------------
                          8.750% Preferred Securities
                          ---------------------------



Dear Ladies and Gentlemen:

          We have acted as tax counsel for BANK ONE CORPORATION, a Delaware
corporation (the "Company"), BANK ONE Capital III, a Delaware business trust
(the "Trust"), and Salomon Smith Barney Inc., Banc One Capital Markets, Inc.,
Credit Suisse First Boston Corporation and Morgan Stanley & Co. Incorporated
(the "Underwriters") in connection with the Registration Statement filed on June
17, 1999 and amended by Amendment No. 1, dated July 6, 1999, the Prospectus
dated July 26, 2000, and the Prospectus Supplement dated August 23, 2000 (the
"Offering Documents"), for the purpose of selling 475,000 8.750% Preferred
Securities (the "Preferred Securities") of the Trust.

          The Preferred Securities represent undivided beneficial interests in
the assets of the Trust.  The Trust's assets will consist of up to $489,691,000
aggregate principal amount of 8.750% Junior Subordinated Deferrable Interest
Debentures due September 1, 2030 (the "Subordinated Debentures") to be issued by
the Company.

          In connection with this opinion, we have examined the Offering
Documents, the Amended and Restated Declaration of Trust, the Certificate of
Trust, the form of the


Preferred Securities and Common Securities and specimen certificates thereof,
the Preferred Securities Guarantee Agreement and the Common Securities Guarantee
Agreement, the Fifth Supplemental Indenture, the executed Underwriting Agreement
and such other documents and corporate records as we have deemed necessary or
appropriate for purposes of our opinion.

          In our examination, we have assumed that (i) the statements concerning
the issuance of the Preferred Securities and Subordinated Debentures referred to
in the Offering Documents are true, correct and complete, (ii) the terms of the
documents listed in the preceding paragraph will be complied with, (iii) the
factual representations made to us by the Company in its letter to us dated as
of the date hereof and delivered to us for purposes of this opinion (the
"Representation Letter") are true, correct and complete and (iv) any factual
representations made in the Offering Documents or the Representation Letter "to
the best knowledge of" or similarly qualified are true, correct and complete
without such qualification.  If any of the above described assumptions are
untrue for any reason or if the issuance of the Preferred Securities and
Subordinated Debentures is consummated in a manner that is inconsistent with the
manner in which it is described in the Offering Documents, our opinion as
expressed below may be adversely affected and may not be relied upon.

          Based solely upon the foregoing, we are of the opinion that under
current United States federal income tax law:

     (1)  The Trust will be classified as a grantor trust and not as an
          association subject to tax as a corporation.  Accordingly, for United
          States federal income tax purposes, each holder of Preferred
          Securities will generally be considered the owner of an undivided
          interest in the Subordinated Debentures.

     (2)  The Subordinated Debentures will be classified for United States
          federal income tax purposes as indebtedness of the Company.

     (3)  Although the discussion set forth in the Prospectus Supplement under
          the heading "United States Federal Income Taxation" does not purport
          to discuss all possible United States federal income tax consequences
          of the purchase, ownership and disposition of Preferred Securities, in
          our opinion such discussion constitutes, in all material respects, a
          fair and accurate summary of the United States federal income tax
          consequences of the purchase, ownership and disposition of


          Preferred Securities under current law.

          Our opinion is limited to the tax matters specifically covered hereby,
and we have not been asked to address, nor have we addressed, any other tax
consequences of the Sale or any other transactions.  Our opinion is based upon
current statutory, regulatory and judicial authority, any of which may be
changed at any time with retroactive effect.  We disclaim any undertaking to
advise you of any subsequent changes of the matters stated, represented or
assumed herein or any subsequent changes in applicable law, regulations or
interpretations thereof.

          We consent to the filing of this opinion as an exhibit to the Form 8-K
to be filed with the Securities and Exchange Commission and to the reference to
our firm name therein.  In giving this consent, we do not admit that we are
within the category of persons whose consent is required under Section 7 of the
Securities Act of 1933, as amended, or the rules or regulations of the
Securities and Exchange Commission promulgated thereunder.

                                                       Very truly yours,



BANK ONE CORPORATION                            /s/ Cravath, Swaine & Moore
   1 BANK ONE PLAZA
      CHICAGO, IL 60670

BANK ONE CAPITAL III
   1 BANK ONE PLAZA
      CHICAGO, ILLINOIS  60670

Salomon Smith Barney Inc.
Banc One Capital Markets, Inc.
Credit Suisse First Boston Corporation
Morgan Stanley & Co. Incorporated
   c/o Salomon Smith Barney Inc.
      388 Greenwich Street
          New York, NY 10013