EXHIBIT (5) & (23)

                        SIDLEY AUSTIN BROWN & WOOD LLP

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                                                             April 12, 2005



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. (hereinafter called
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 the Underwriters named in the
Terms Agreement referred to below, pursuant to an Underwriting Agreement,
dated December 3, 2004 (the "Underwriting Agreement"), between the Company and
Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated
("MLPF&S"), as supplemented by the Terms Agreement, dated April 6, 2005 (the
"Terms Agreement"), among the Company, MLPF&S and Morgan Stanley & Co.
Incorporated, of the Company's 6.75% Mandatorily Exchangeable Securities due
October 15, 2007, Mandatorily Exchangeable for Shares of Class A Common Stock
of Nuveen Investments, Inc. (the "Securities") in an amount equal to





$275,060,000 aggregate principal amount of the Securities. We have also
examined a copy of the Indenture between the Company and JPMorgan Chase Bank,
N.A. as Trustee, dated as of April 1, 1983, as amended (the "Indenture"), and
the Company's Registration Statement on Form S-3 (File No. 333-122639)
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 as the enforcement thereof may be limited by bankruptcy,
insolvency, reorganization, moratorium, fraudulent conveyance, fraudulent
transfer and other similar laws relating to or affecting creditors' generally
and to general equitable principles (regardless of whether considered in a
proceeding in equity or at law), including concepts of commercial
reasonableness, good faith and fair dealing and the possible unavailability of
specific performance or injunctive relief.

         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 April 12, 2005. We also consent to the use of our name under
the caption "United States Federal Income Taxation" in the prospectus
supplement related to the offering of the Securities.

                                            Very truly yours,


                                            \s\ Sidley Austin Brown & Wood LLP