November 24, 1997
PaineWebber Incorporated
1200 Harbor Boulevard
Weehawken, New Jersey  07087
Dear Sirs:
 As counsel for PaineWebber Incorporated (the 
"Depositor"), we have examined an executed copy of the 
Trust Indenture and Agreement dated the date of initial 
deposit of the Trust  (the "Indenture") which 
incorporates the Standard Terms and Conditions of Trust  
(the "Agreement"), both between the Depositor, and 
Investors Bank & Trust Company and the First National 
Bank of Chicago as Co-Trustees (the "Trustee").  The 
Indenture established a trust called Municipal Bond 
Trust, Series 231 (the "Trust") into which the 
Depositor deposited certain debt obligations issued by 
or on behalf of one or more of the States or 
territories of the United States, any political 
subdivision thereof or any public instrumentality or 
agency thereof or evidences thereof, (the 
"Securities"), and moneys to be held by the Trustee 
upon the terms and conditions set forth in the 
Indenture and Agreement.  Under the Indenture, 
certificates of ownership were issued on the Initial 
Date of Deposit representing units of fractional 
undivided interest in said Trust (the "Units").
 Based upon the foregoing and upon an examination of 
such other documents and an investigation of such 
matters of law as we have deemed necessary, we are of 
the opinion that, under existing statutes and 
decisions:
 (i) The Trust is not an association taxable as a
corporation for U.S. federal income tax purposes but 
will be governed by the provisions of Subchapter J
(relating to Trusts) of Chapter 1, Internal Revenue Code
of 1986 (the "Code").  Each Unitholder will be considered
as owning a pro rata share of each asset of the respective
Trust in the proportion that the number of Units of such 
Trust held by him bears to the total number of 
outstanding Units of such Trust.  Under Subpart E, 
Subchapter J of Chapter I of the Code, income of the 
Trust will be treated as income of each Unitholder of 
the Trust in the proportion described.  Accordingly, to 
the extent that the income of the Trust consists of 
interest and original issue discount excludable from 
gross income under Section 103 of the Code, such income 
will be excludable from federal gross income of the 
Unitholder, except in the case of a Unitholder who is a 
substantial user (or a person related to such user) of 
a facility financed through issuance of any industrial 
development bonds or certain private activity bonds 
held by the Trust.  All taxpayers are nevertheless 
required to disclose to the Internal Revenue Service 
the amount of tax-exempt interest earned during the 
year.  In the case of certain corporations, interest on 
all of the Securities is included in computing the 
alternative minimum taxable income pursuant to Section 
56(c) of the Code.
 (ii) If the Trustee disposes of a Security (whether by 
sale, payment at maturity, redemption or otherwise), 
gain or loss is recognized to the Unitholder. A Unitholder
will also be considered to have disposed of all or a 
portion of his pro rata portion of each Security when 
he sells or redeems some or all of his Units.  Such 
gain or loss is measured by comparing the Unitholder's 
share of such proceeds (or, in the case of a sale or 
redemption of Units, the portion of the proceeds 
allocable to a Security) with the Unitholder's adjusted 
basis for such Security. 
 (iii) Under the income tax laws of the State and City 
of New York, the Trust is not an association taxable as 
a corporation and income received by the Trust will be 
treated as the income of the Unitholders in the same 
manner as for federal income tax purposes, but will not 
be tax-exempt except to the extent that such income is 
earned on bonds in the Trust that are otherwise tax-
exempt for New York purposes.
 We hereby consent to the filing of this opinion as an 
exhibit to the Registration Statement relating to the 
Units and the Trust referred to above and to the use of 
our name and to the reference to our firm in said 
Registration Statement and in the related Prospectus.
Very truly yours,
/s/ CARTER, LEDYARD & MILBURN