Exhibits (5) & (23)


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                                                                  May 16, 2006



Merrill Lynch & Co., Inc.
4 World Financial Center
New York, New York 10080

Ladies and Gentlemen:

      As your counsel, we have examined a copy of the Restated Certificate of
Incorporation, as amended, of Merrill Lynch & Co., Inc. (the "Company"),
certified by the Secretary of State of the State of Delaware. We are familiar
with the corporate proceedings had in connection with the proposed issuance
and sale by the Company to Merrill Lynch, Pierce, Fenner & Smith Incorporated
("MLPF&S"), HSBC Securities (USA) Inc. and Wachovia Capital Markets, LLC
(collectively, the "Underwriters") pursuant to an Underwriting Agreement dated
March 31, 2006 (the "Underwriting Agreement") between the Company and MLPF&S,
as supplemented by the Terms Agreement dated May 11, 2006 (the "Terms
Agreement") between the Company and the Underwriters, of the Company's 6.050%
Subordinated Notes due May 16, 2016 (the "Securities") in an amount equal to
$2,000,000,000 aggregate principal amount of the Securities. We have also
examined a copy of the indenture dated as of December 17, 1996, as amended
through the date hereof, including pursuant to the Supplemental Indenture
dated as of the date


hereof (as so amended, the "Indenture"), between the Company and JPMorgan
Chase Bank, N.A. as Trustee, and the Company's Registration Statement on Form
S-3 (File No. 333-132911) relating to the Securities (the "Registration
Statement").

      Based upon the foregoing and upon such further investigation as we
deemed relevant in the premises, we are of the opinion that:

      1. The Company has been duly incorporated under the laws of the State of
Delaware.

      2. The Securities have been duly and validly authorized by the Company
and, when the Securities have been duly executed and authenticated in
accordance with the terms of the Indenture and delivered against payment
therefor as set forth in the Underwriting Agreement, as supplemented by the
Terms Agreement, the Securities will constitute valid and legally binding
obligations of the Company, enforceable against the Company in accordance with
their terms, except to the extent that enforcement thereof may be limited by
bankruptcy, moratorium, insolvency, reorganization or similar laws relating to
or affecting creditors' rights generally and except as enforcement thereof is
subject to general principles at equity (regardless of whether enforcement is
considered in a proceeding in equity or at law).

      We consent to the filing of this opinion as an exhibit to the
Registration Statement and as an exhibit to the Current Report of the Company
on Form 8-K dated May 16, 2006. We also consent to the use of our name under
the caption "United States Federal Income Taxation" in the terms supplement
related to the offering of the Securities.



                                                    Very truly yours,


                                                    /s/ Sidley Austin LLP