Exhibit 8.1
                                                                     -----------



                                            August 29, 2002




                                               
Standard & Poor's,                                Credit Suisse First Boston Corporation
 a division of The McGraw-Hill Companies, Inc.    Eleven Madison Avenue
55 Water Street                                   New York, NY 10010
New York, NY 10041-0003

Moody's Investors Service, Inc.                   Lehman Brothers Inc.
99 Church Street                                  745 Seventh Avenue
New York, NY 10007                                New York, NY 10019

Deutsche Bank National Trust Company
1761 East Street, Andrew Place
Santa Ana, California 92705-4934



          Re:  IndyMac MBS, Inc.
               Residential Asset Securitization Trust, Series 2002-A10
               Mortgage-Pass Through Certificates, Series 2002-J
               -------------------------------------------------


Ladies and Gentlemen:

     We have acted as special counsel for IndyMac MBS, Inc., a Delaware
corporation (the "Depositor"), in connection with (i) the sale by IndyMac Bank,
F.S.B., a federal savings bank ("IndyMac Bank"), and the purchase by the
Depositor, of a pool of Mortgage Loans (as defined below) and (ii) the
simultaneous sale by the Depositor of that pool of Mortgage Loans to Deutsche
Bank National Trust Company as trustee (the "Trustee") in connection with the
issuance of the Mortgage Pass-Through Certificates, Series 2002-A-10, Class
I-A-1, Class I-X-A-1,




Class II-A-1, Class II-X-A-1 and Class A-R Certificates (the "Publicly Offered
Senior Certificates"), the Class B-1, Class B-2 and Class B-3 Certificates (the
"Publicly Offered Subordinate Certificates" and, together with the Publicly
Offered Senior Certificates, the "Publicly Offered Certificates") and the Class
B-4, Class B-5 and Class B-6 Certificates (the "Non-Publicly Offered
Certificates" and, together with the Publicly Offered Certificates, the
"Certificates"). A trust (the "Trust") is being formed and the Certificates are
being issued pursuant to a Pooling and Servicing Agreement, dated as of August
1, 2002 (the "Pooling and Servicing Agreement"), among the Depositor, as
depositor, IndyMac Bank, as seller and master servicer, and the Trustee. A
"Mortgage Loan" means a conventional adjustable-rate mortgage loan secured by a
first lien on a one-to four-family residential property sold on the Closing
Date pursuant to the Pooling and Servicing Agreement. Capitalized terms not
otherwise defined in this opinion letter are used as defined in the Pooling and
Servicing Agreement.

On the Closing Date, the Trustee will issue the Certificates in the name or at
the direction of the Depositor and will transfer the Certificates to the
Depositor in consideration for the sale of the Mortgage Loans from the
Depositor to the Trustee. Upon receipt of the Certificates on the Closing Date,
the Depositor (i) will sell the Publicly Offered Senior Certificates (other
than the Class I-X-A-1 and the Class II-X-A-1 Certificates, which are being
retained by IndyMac Bank) to Credit Suisse First Boston Corporation pursuant to
an underwriting agreement (ii) will sell the Publicly Offered Subordinate
Certificates to Lehman Brothers Inc. ("Lehman") pursuant to an underwriting
agreement (iii) will sell the Non-Publicly Offered Certificates to Lehman
pursuant to a purchase agreement and (iv) will remit the proceeds of those
sales, together with the Class I-X-A-1 and the Class II-X-A-1 Certificates to
IndyMac Bank in consideration for the sale of the Mortgage Loans from IndyMac
Bank to the Depositor.

     When we make assumptions for the purposes of expressing the opinions set
forth below or when we express no opinion or qualify or limit an opinion as to
certain matters or when we state that we rely on certificates, documents, or
other matters, in each case we do so with the permission of each addressee of
this letter.

     In connection with rendering this opinion, we have examined the Pooling and
Servicing Agreement and such other documents, certificates, and records, and
have performed such investigations of law, as we have deemed necessary or
appropriate as a basis for our opinion. Further, we have assumed the genuineness
of all signatures, the authenticity of all documents submitted to us as
originals, the conformity to originals of all documents submitted to us as
copies or specimens, the authenticity of the originals of such documents
submitted to us as copies or specimens, the accuracy of the matters set forth in
the documents we have reviewed and the due authorization, execution, and
delivery of the Pooling and Servicing Agreement by the parties thereto. We have
also assumed that no agreements or understandings between the parties exist
regarding the transactions contemplated in the Pooling and Servicing Agreement,
other than those contained therein.

     As of the Closing Date, each REMIC created pursuant to the Pooling and
Servicing Agreement will qualify as a REMIC within the meaning of Section
860D of the Internal Revenue Code of 1986, as amended (the "Code"), assuming (i)
an election is made with respect to each REMIC and (ii) compliance with changes
in the law, including any amendments to the Code or applicable Treasury
regulations thereunder. The Certificates (other than the Class A-R





Certificates) represent ownership of regular interests in the Master REMIC. The
Class A-R Certificates represent ownership of the sole class of residual
interest in each REMIC.

     The opinions set forth in this opinion letter are based upon the existing
provisions of the Code and Treasury regulations issued or proposed thereunder,
published Revenue Rulings and releases of the Internal Revenue Service and
existing case law, any of which could be changed at any time. Any such changes
may be retroactive in application and could modify the legal conclusions upon
which such opinions are based. The opinions expressed herein are limited as
described above, and we do not express an opinion on any other tax aspect of
the transactions contemplated by the documents relating to the transaction.

     In rendering the foregoing opinions, we express no opinion as to the laws
of any jurisdiction other than the federal income tax laws of the United
States. This opinion is rendered as of the date hereof and we undertake no
obligation to update this opinion or advise you of any changes in the event
there is any change in legal authorities, facts, assumptions or documents on
which this opinion is based (including the taking of any action by any party
to the Documents pursuant to any opinion of counsel or a waiver), or any
inaccuracy in any of the representations, warranties or assumptions upon which
we have relied in rendering this opinion unless we are specifically engaged to
do so. This opinion is rendered only to those to whom it is addressed and may
not be relied on in connection with any transactions other than the
transactions contemplated herein. This opinion may not be relied upon for any
other purpose, or relied upon by any other person, firm or corporation for any
purpose, without our prior written consent.

                                         Very truly yours,

                                         /s/ Sidley Austin Brown & Wood LLP
                                         ----------------------------------

                                         Sidley Austin Brown & Wood LLP