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<TYPE>EX-12
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<FILENAME>efc4-1239_5564351ex12.txt
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                                                                    EXHIBIT 12



                        SIDLEY AUSTIN BROWN & WOOD LLP

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 LONDON                                                         WASHINGTON, D.C.






                                               June 7, 2004



MuniYield Insured Fund, Inc.
800 Scudders Mill Road
Plainsboro, New Jersey  08536

MuniInsured Fund, Inc.
800 Scudders Mill Road
Plainsboro, New Jersey  08536

          Re:  Reorganization of MuniYield Insured Fund, Inc.
               and MuniInsured Fund, Inc.
               ----------------------------------------------

Ladies and Gentlemen:

     You have requested our opinion as to certain Federal income tax
consequences of the acquisition by MuniYield Insured Fund, Inc. ("MuniYield"),
of substantially all of the assets of, and the assumption by MuniYield of
substantially all of the liabilities of, MuniInsured Fund, Inc.
("MuniInsured"), and the simultaneous distribution of newly-issued shares of
common stock, par value $.10 per share (the "Reorganization"), to the
stockholders of MuniInsured. After the Reorganization, MuniInsured will cease
to operate, will have no assets remaining, will have final Federal and state
(if any) tax returns filed on its behalf and will have all of its shares
cancelled under Maryland law.

     This opinion letter is furnished pursuant to (i) the sections entitled
"Agreement and Plan of Reorganization - Procedure" and "Agreement and Plan of
Reorganization - Terms of the Agreement and Plan of Reorganization -
Amendments and Conditions" in the Joint Proxy Statement and Prospectus, dated
April 15, 2004, contained in the Registration Statement on Form N-14 (File No.
333-113433) of MuniYield, as amended and supplemented to date (the "N-14
Registration Statement"), and (ii) Sections 8(g) and 9(h) of the Agreement and
Plan of Reorganization, dated April 14, 2004, by and between MuniYield and
MuniInsured (the "Plan")


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Sidley Austin Brown & Wood LLP
                                                                      New York
MuniYield Insured Fund, Inc.
MuniInsured Fund, Inc.
June 7, 2004
Page 2






as a condition of closing. All terms used herein, unless otherwise defined,
are used as defined in the Plan.

     In rendering our opinion, we have reviewed and relied upon (a) the Plan,
(b) the N-14 Registration Statement and (c) certain representations concerning
the Reorganization made by (i) MuniYield in a letter dated June 7, 2004 and
(ii) MuniInsured in a letter dated June 7, 2004 (together, the
"Representations").

     Based upon current law, including cases and administrative
interpretations thereof and on the reviewed materials listed above, it is our
opinion that:

     1. The acquisition by MuniYield of substantially all of the assets of
MuniInsured, as described in the Plan, will constitute a reorganization within
the meaning of section 368(a)(1)(C) of the Internal Revenue Code of 1986, as
amended (the "Code"), and MuniYield and MuniInsured will each be a "party" to
a reorganization within the meaning of section 368(b) of the Code.

     2. In accordance with section 361(a) of the Code, MuniInsured will not
recognize any gain or loss either on the transfer of substantially all of its
assets to MuniYield in exchange solely for shares of common stock of MuniYield
("MuniYield common stock") or on the simultaneous distribution of MuniYield
common stock to the stockholders of MuniInsured.

     3. Under section 1032 of the Code, MuniYield will recognize no gain or
loss as a result of the Reorganization.

     4. In accordance with section 354(a)(1) of the Code, stockholders of
MuniInsured will recognize no gain or loss on the exchange of their
corresponding shares of common stock of MuniInsured solely for shares of
common stock of MuniYield, except to the extent that a stockholder of
MuniInsured receives cash in lieu of fractional shares of common stock of
MuniYield.

     5. The basis of the assets of MuniInsured received by MuniYield will be
the same as the basis of such assets to MuniInsured immediately before the
Reorganization under section 362(b) of the Code.

     6. Under section 358 of the Code, the basis of the shares of common stock
of MuniYield received by stockholders of MuniInsured will be the same as the
basis of the corresponding shares of common stock of MuniInsured exchanged
pursuant to the Reorganization.


<PAGE>


Sidley Austin Brown & Wood LLP
                                                                      New York
MuniYield Insured Fund, Inc.
MuniInsured Fund, Inc.
June 7, 2004
Page 3






     7. Under section 1223 of the Code, the holding period of the shares of
common stock of MuniYield received in the Reorganization will include the
holding period of the corresponding shares of common stock of MuniInsured
exchanged pursuant to the Reorganization, provided that such shares of common
stock were held as a capital asset on the date of the Reorganization.

     8. The holding period of the assets acquired by MuniYield from
MuniInsured will include the period during which such assets were held by
MuniInsured under section 1223 of the Code.

     9. The payment of cash to stockholders of MuniInsured in lieu of
fractional shares of common stock of MuniYield will be treated as though the
fractional shares were distributed as part of the Reorganization and then
redeemed by MuniYield. The cash payment will be treated as a distribution in
full payment for the fractional share of common stock of MuniInsured deemed
redeemed under section 302(a) of the Code, with the result that such
MuniInsured stockholder will have short-term or long-term capital gain or loss
to the extent that the cash distribution differs from the basis allocable to
such stockholder's fractional share.

     10. Pursuant to section 381(a) of the Code and section 1.381(a)-1 of the
Income Tax Regulations, MuniYield will succeed to and take into account the
items of MuniInsured described in section 381(c) of the Code, subject to the
provisions and limitations specified in sections 381, 382, 383 and 384 of the
Code and the regulations thereunder. Under section 381(b) of the Code, the tax
year of MuniInsured will end on the date of the Reorganization.

     Our opinion represents our best legal judgment with respect to the proper
Federal income tax treatment of the Reorganization, based on the facts
contained in the Plan, the N-14 Registration Statement and the
Representations. Our opinion assumes the accuracy of the facts as described in
the Plan, the N-14 Registration Statement and the Representations and could be
affected if any of the facts as so described are inaccurate.

     We are furnishing this opinion letter to the addressees hereof, solely
for the benefit of such addressees in connection with the Reorganization. This
opinion letter is not to be used, circulated, quoted or otherwise referred to
for any other purpose.

                                    Very truly yours,
                                    /s/ Sidley Austin Brown & Wood LLP

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