OPINION RE: LEGALITY; CONSENT OF COUNSEL

EXHIBIT (5) & (23)



May 23, 2001

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

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 Underwriter named in the Terms Agreement
referred to below, pursuant to an Underwriting Agreement dated August 5, 1998
(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 May 18, 2001 (the "Terms Agreement") between the
Company and MLPF&S (the "Underwriter"), of $4,600,000,000 aggregate principal
amount at maturity of the Company's Liquid Yield Option Notes due 2031 (the
"Notes"). We have also examined a copy of the Indenture between the Company and
The Chase Manhattan Bank as Trustee, dated as of May 23, 2001 (the "Indenture"),
and the Company's Registration Statement on Form S-3 (File No. 333-52822)
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 Notes have been duly and validly authorized by the Company and when
the Notes 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 Notes 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
Statements and as an exhibit to the Current Report of the Company on Form 8-K
dated May 23, 2001.

Very truly yours,

/s/ Sidley Austin Brown & Wood LLP