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                                                                     EXHIBIT 5.1

                      [ANDREWS & KURTH L.L.P. LETTERHEAD]



                               October 10, 2000



First Horizon Asset Securities Inc.
4000 Horizon Way
Irving, Texas 75063

     Re:  First Horizon Asset Securities Inc.
          Registration Statement on Form S-3 (the "Registration Statement")

Ladies and Gentlemen:

     We have acted as special counsel for First Horizon Asset Securities Inc., a
corporation organized under the laws of the State of Delaware (the "Company"),
in connection with the proposed issuance by the Company or a special purpose
trust established by the Company as issuer (the "Issuer") of Mortgage and Asset-
Backed Securities (the "Securities"). The Securities of a series are to be
issued pursuant to (a), in the case of a series of pass-through certificates, a
Pooling and Servicing Agreement, by and among the Company, as depositor, a
seller, a master servicer and a trustee, or (b), in the case of a series of
notes, an Indenture, by and between the Issuer and a trustee, in each case
authorizing the issuance of such series. The Pooling and Servicing Agreement, in
the form incorporated by reference as Exhibit 4.1 to the Registration Statement,
and the Indenture in the form filed as Exhibit 4.2 to the Registration
Statement, are each referred to herein as an "Agreement."

     We have examined originals or copies, certified or otherwise identified to
our satisfaction, of the Company's organizational documents, the form of each
Agreement and the form of Securities included therein and such other documents,
records, certificates of the Company and public officials and other instruments
as we have deemed necessary for the purposes of rendering this opinion. In
addition, we have assumed that each Agreement as completed for each series will
be duly executed and delivered by each of the parties thereto; that the
Securities as completed for each series will be duly executed and delivered
substantially in the form contemplated by the applicable Agreement; that the
Securities for each series will be offered and sold as described in the
Registration Statement; and that the Agreements and the Securities constitute
legal, valid and enforceable obligations of the parties thereto (other than the
Issuer).
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First Horizon Asset Securities Inc.
October 10, 2000
Page 2

     Based upon the foregoing and subject to the limitations and qualifications
set forth below, we are of the opinion that:

     1.   When any Agreement relating to a series of Securities has been duly
and validly authorized by all necessary action on the part of the Issuer
(subject to the terms thereof being otherwise in compliance with applicable law
at such time) and has been duly executed and delivered by the Issuer, the master
servicer, if any, the applicable trustee, and any other party thereto, such
Agreement will constitute a legal, valid and binding agreement of the Issuer,
enforceable against the Issuer in accordance with its terms, except that the
enforceability thereof may be subject to (a) bankruptcy, insolvency,
reorganization, arrangement, moratorium, fraudulent or preferential conveyance
or other similar laws now or hereinafter in effect relating to creditors' rights
generally, and (b) general principals of equity (regardless of whether such
enforceability is considered in a proceeding in equity or at law).

     2.   When a series of Securities has been duly authorized by all necessary
action on the part of the Issuer (subject to the terms thereof being otherwise
in compliance with applicable law at such time), duly executed and authenticated
by the applicable trustee for such series in accordance with the terms of the
related Agreement and issued and delivered against payment therefor as described
in the Registration Statement, such series of Securities will be (a) in the case
of a series of pass-through certificates, legally and validly issued, fully paid
and nonassessable, and the holders thereof will be entitled to the benefits of
the related Pooling and Servicing Agreement, and (b) in the case of a series of
notes, valid and binding obligations of the Issuer, enforceable against the
Issuer in accordance with their terms, except that the enforceability thereof
may be subject to (i) bankruptcy, insolvency, reorganization, arrangement,
moratorium, fraudulent or preferential conveyance or other similar laws now or
hereinafter in effect relating to creditors' rights generally, and (ii) general
principals of equity (regardless of whether such enforceability is considered in
a proceeding in equity or at law).

     The opinions expressed above are subject to the qualification that we do
not purport to be experts as to the laws of any jurisdiction other than the
United States of America and the laws of the States of Texas and New York, and
we express no opinion herein as to the effect that the laws and decisions of
courts of any such other jurisdiction may have upon such opinions.
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First Horizon Asset Securities Inc.
October 10, 2000
Page 3


     We consent to the use and filing of this opinion letter as Exhibit 5.1 to
the Registration Statement and to the reference to our firm under the caption
"Legal Matters" in the Prospectus Supplement and Prospectus contained therein.
In giving such consent we do not imply or admit that we are within the category
of persons whose consent is required under Section 7 of the Securities Act of
1933, as amended, or the rules and regulations of the Securities and Exchange
Commission thereunder.



                                             Very truly yours,

                                             ANDREWS & KURTH L.L.P.



                                             By: /s/ David Barbour
                                                --------------------------
                                                    David Barbour, Partner