[Letterhead of Brown & Wood LLP]

                                                                    Exhibit 5(a)



                                                 January 27, 1998



Merrill Lynch & Co., Inc.
World Financial Center
North Tower
New York, New York  10281-1334

Ladies and Gentlemen:

     We have acted as your counsel and are familiar with the corporate
proceedings had in connection with the proposed issuance and sale by Merrill
Lynch & Co., Inc. (the "Company") of up to $8,000,000,000 aggregate principal
amount of its senior debt securities, including Structured Yield Product
Exchangeable for Stock, (the "Senior Debt Securities") and/or subordinated debt
securities (the "Subordinated Debt Securities", and together with the Senior
Debt Securities, the "Debt Securities"), both of which may be convertible into
common stock, par value $1.33 1/3 per share, of the Company (the "Common
Stock"), preferred stock, par value $1.00 per share, of the Company (the
"Preferred Stock") or Depositary Shares representing Preferred Stock (the
"Depositary Shares"); and/or warrants to purchase Debt Securities (the "Debt
Warrants"); and/or warrants entitling the holders thereof to receive from the
Company a payment or delivery determined by reference to decreases or increases
in the level of an index or portfolio based on one or more equity or debt
securities, any statistical measure of economic or financial performance, or the
price or value of any commodity or any other item or index or a combination
thereof (the "Index Warrants"); and/or warrants to receive from the Company the
cash value in U.S. dollars of the right to purchase or to sell specified foreign
currencies or units of two or more such foreign currencies (the "Currency
Warrants"); and/or shares of Preferred Stock, which may be convertible into
Preferred Stock or Common Stock or exchangeable for Debt Securities; and/or
shares of Preferred Stock, which may be represented by Depositary Shares; and/or
warrants to purchase shares of Preferred Stock (the "Preferred Stock Warrants");
and/or shares of Common Stock; and/or warrants to purchase shares of Common
Stock (the "Common Stock Warrants"), in each case as shall be designated by the
Company at the time of offering.

     We have examined such documents and records as we deemed appropriate,
including the following:

 
     (a)  a copy of the Restated Certificate of Incorporation of the Company,
          certified by the Secretary of State of the State of Delaware;

     (b)  copies of the Company's Registration Statement on Form S-3 (File No.
          333-44173), as amended, relating to the Securities (as defined below)
          (the "Registration State ment");

     (c)  a copy of the indenture with respect to the Senior Debt Securities
          between the Company and The Chase Manhattan Bank (formerly known as
          Chemical Bank, successor by merger to Manufacturers Hanover Trust
          Company), as trustee, dated April 1, 1983, as amended and restated
          (the "1983 Senior Indenture"), in the form executed by the Company and
          The Chase Manhattan Bank;

     (d)  a copy of the indenture with respect to the Senior Debt Securities
          between the Company and The Chase Manhattan Bank (successor by merger
          to The Chase Manhattan Bank, N.A.), as trustee, dated October 1, 1993
          (the "1993 Senior Indenture"), in the form executed by the Company and
          The Chase Manhattan Bank;

     (e)  a copy of the supplemental indenture with respect to the Senior Debt
          Securities between the Company and The Chase Manhattan Bank, as
          successor trustee, dated October 25, 1993 (the "1993 Supplemental
          Indenture") in the form executed by the Company and The Chase
          Manhattan Bank;

     (f)  a copy of the indenture with respect to the Subordinated Debt
          Securities between the Company and The Chase Manhattan Bank, as
          trustee, dated December 17, 1996 (the "Subordinated Indenture"), in
          the form executed by the Company and The Chase Manhattan Bank;

     (g)  a copy of the form of indenture with respect to Index Warrants which
          are to be issued with a minimum value pay able upon expiration (a
          "Minimum Expiration Value") (including a form of global index warrant
          certificate) (the "Index Warrant Indenture") in the form filed or
          incorporated by reference as an exhibit to the Registra tion
          Statement;

     (h)  a copy of the form of warrant agreement with respect to Index Warrants
          other than Index Warrants which are to be issued with a Minimum
          Expiration Value (including a form of global index warrant
          certificate) (the "Index Warrant Agreement") in the form filed or
          incorporated by refer ence as an exhibit to the Registration
          Statement;

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     (i)  a copy of the form of warrant agreement with respect to the Debt
          Warrants (including a form of global debt warrant certificate) (the
          "Debt Warrant Agreement") in the form filed or incorporated by
          reference as an exhibit to the Registration Statement;

     (j)  a copy of the form of warrant agreement with respect to the Currency
          Warrants (including a form of global currency warrant certificate)
          (the "Currency Warrant Agreement") in the form filed or incorporated
          by refer ence as an exhibit to the Registration Statement;

     (k)  a copy of the form of warrant agreement with respect to the Preferred
          Stock Warrants and the Common Stock Warrants (including a form of
          global warrant certificate) (the "Preferred Stock and Common Stock
          Warrant Agreement") in the form filed or incorporated by reference as
          an exhibit to the Registration Statement;

     (l)  a copy of the form of certificate of designations with respect to the
          Preferred Stock (the "Certificate of Designations") in the form filed
          or incorporated by reference as an exhibit to the Registration
          Statement;

     (m)  a copy of the form of deposit agreement with respect to the Depositary
          Shares (the "Deposit Agreement") in the form filed or incorporated by
          reference as an exhibit to the Registration Statement;

     (n)  a copy of the form of certificate representing the Preferred Stock in
          the form filed or incorporated by reference as an exhibit to the
          Registration Statement; and

     (o)  a specimen of the certificate representing the Common Stock in the
          form filed or incorporated by reference as an exhibit to the
          Registration Statement.

     The Debt Warrants, Index Warrants, Currency Warrants, Preferred Stock
Warrants and Common Stock Warrants are hereinafter collectively referred to as
the "Warrants".  The Warrants, Debt Securities, Preferred Stock, Depositary
Shares and Common Stock are hereinafter collectively referred to as the
"Securities".  The "1983 Senior Indenture" shall mean such indenture as amended
by the Trust Indenture Reform Act of 1990.  The 1983 Senior Indenture, 1993
Senior Indenture and the 1993 Senior Indenture as supplemented by the 1993
Supplemental Indenture are hereinafter collectively referred to as the "Senior
Indentures".  The Senior Indentures, Subordinated Indenture and Index Warrant
Indenture, including any supplemental indenture thereto, are hereinafter
collectively referred to as the "Indentures".  The Debt Warrant Agreement,
Currency Warrant Agreement, Index Warrant Agreement and Preferred

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Stock and Common Stock Warrant Agreement are hereinafter collectively referred
to as the "Warrant Agreements".

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

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

     2.   The Senior Indentures and the Subordinated Indenture have each been
duly and validly authorized, executed and delivered by the Company and, as
amended by the Trust Indenture Reform Act of 1990, constitute valid and binding
agreements of the Company, enforceable in accordance with their respective
terms.

     3.   When appropriate corporate action has been taken to authorize the
Company to execute and deliver any applicable Index Warrant Indenture,
supplemental indenture or Warrant Agreement, to fix the terms of one or more
issues of Securities under an Inden ture or Warrant Agreement and to authorize
their issue, and such Indenture or Warrant Agreement shall have been duly
executed and delivered by the Company and the trustee or warrant agent, and when
the Securities with terms so fixed shall have been duly authenticated or
countersigned by the trustee or warrant agent, as the case may be, and duly
issued under the respective Indenture or Warrant Agreement in accordance with
such corporate action, such Indentures and/or Warrant Agreements and such
Securities will constitute valid and binding agreements of the Company,
enforceable in accordance with their terms.

     4.   When appropriate corporate action has been taken by the Company to fix
the terms of one or more series of the Preferred Stock as contemplated in the
Registration Statement, to authorize the execution and filing with the Secretary
of State of the State of Delaware of a Certificate of Designations relating
thereto and to authorize the issuance of shares thereof, and when such
Certificate of Designations shall have been so executed and filed by the Company
and Preferred Stock with the terms so fixed shall have been duly issued and
delivered by the Company against payment of the consideration therefor or for
Depositary Shares representing interests therein in accordance with such
corporate action, such Preferred Stock will be validly issued, fully paid and
non-assessable.

     5.   When appropriate corporate action has been taken by the Company to
authorize the execution and delivery of a Deposit Agreement, and when such
Deposit Agreement shall have been duly executed and delivered by the Company and
the depositary, such Deposit Agreement will constitute a valid and binding
agreement of the Company, enforceable in accordance with its terms.

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     6.   When appropriate corporate action has been taken by the Company to
authorize the issuance and deposit of Preferred Stock with a depositary pursuant
to a Depositary Agreement and the issuance of Depositary Shares representing
interests therein, and when such Preferred Stock shall have been duly issued and
so deposited and such depositary shall have duly issued and delivered depositary
receipts evidencing such Depositary Shares against payment of the consideration
therefor in accordance with such corporate action, such Depositary Shares will
represent valid interests in the Preferred Stock so deposited and shall entitle
the holders thereof to the rights specified in the depositary receipts
evidencing the Depositary Shares and in the applicable Deposit Agreement.

     7.   When appropriate corporate action has been taken by the Company to
authorize the issuance of shares of Common Stock, such Common Stock, when
issued, delivered and paid for as contemplated in the Registration Statement,
will be duly authorized, validly issued, fully paid and non-assessable.

     With respect to enforcement, the above opinions are qualified to the extent
that enforcement of the Indentures, Warrant Agree ments, Securities and Deposit
Agreement may be limited by bankruptcy, insolvency or other laws of general
applicability relating to or affecting enforcement of creditors' rights or by
general equity principles, and further to the extent that enforcement of any
Securities denominated in other than United States dollars may be limited by
requirements that a claim (or foreign currency judgment in respect of such
claim) be converted into United States dollars at a rate of exchange prevailing
on a date determined pursuant to applicable law.  We have further assumed with
respect to enforcement that, when fixed, the terms of the Securities will comply
with all applicable "bucket shop" or similar state laws, or have the
availability of federal preemption therefrom.

     We consent to the filing of this opinion as an exhibit to the Registration
Statement and to the use of our name wherever appearing in the Registration
Statement and any amendment thereto.

                                            Very truly yours,

                                            /s/ BROWN & WOOD LLP
 

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