As filed with the Securities and Exchange Commission on April 25, 2005
                                                   Registration No. 333-______

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                       FIRST HORIZON NATIONAL CORPORATION
             (Exact name of registrant as specified in its charter)

         TENNESSEE                                        62-0803242
(State or other jurisdiction of                       (I.R.S. Employer
 incorporation or organization)                       Identification No.)

                               165 Madison Avenue
                            Memphis, Tennessee 38103
                                 (901) 523-4444
              (Address, including zip code, and telephone number,
        including area code, of registrant's principal executive offices)

              First Horizon Nonqualified Deferred Compensation Plan
                              (Full title of plan)

Harry A. Johnson, III                      With a copy to:
Executive Vice President and
    General Counsel                        Clyde A.  Billings, Jr.
First Horizon National Corporation         Senior Vice President, Assistant
165 Madison Avenue                         General Counsel and
Memphis, Tennessee  38103                  Corporate Secretary
(901) 523-5624                             First Horizon National Corporation
(Name, address, including zip code,        165 Madison Avenue
 and telephone number, including area      Memphis, TN  38103
 code, of agent for service)               (901) 523-5679


                         CALCULATION OF REGISTRATION FEE
=========================================================================
Title of    Amount to be   Proposed Maxi-   Proposed Maxi-  Amount of
Securities  Registered     mum Offering     mum Aggregate   Registration
To be                      Price per        Offering        Fee (1)
Registered                 Share (1)        Price (1)
----------  ------------   --------------   --------------  -------------
Deferred    $60,000,000    100%             $60,000,000     $7,062.00
Compensation
Obligations
=========================================================================

(1) Estimated solely for the purpose of calculating the registration fee.



Note on Filing History

     On June  11,  2003,  First  Horizon  National  Corporation  ("FHNC"  or the
"Registrant") filed a registration  statement on Form S-8 (File No. 333-106015),
registering $30,000,000 of deferred compensation obligations to be offered under
the  First  Horizon  Nonqualified   Deferred  Compensation  Plan  (the  "Plan").
Registrant  is filing this  registration  statement  to  register an  additional
$60,000,000 of deferred compensation obligations under the Plan.


                                     PART I

     The Section  10(a)  prospectus  relating  to the Plan is omitted  from this
Registration Statement pursuant to the Note to Part I of Form S-8.


                                     PART II
                 INFORMATION REQUIRED IN REGISTRATION STATEMENT

     As permitted  by  Instruction  E to Form S-8, the contents of  Registrant's
registration  statement on Form S-8 (File No. 333-106015),  which was filed June
11, 2003,  covering  deferred  compensation  obligations to be offered under the
Plan, as updated below, are incorporated herein by reference. In addition to the
foregoing,  the  following  information  is also  included in this  registration
statement:

Item 5.  Interests of Named Experts and Counsel

     The  validity of the deferred  compensation  obligations  of First  Horizon
National  Corporation  ("FHNC" or the "Registrant") to be issued pursuant to the
Plan has been  passed upon by Clyde A.  Billings,  Jr.,  Senior Vice  President,
Assistant General Counsel and Corporate Secretary of FHNC. On April 1, 2005, the
number of shares,  including  options,  beneficially  owned by Mr.  Billings was
approximately 47,934 shares, and the amount of deferred compensation owed to Mr.
Billings by FHNC (under a separate plan) was approximately $23,000.

Item 8.  Exhibits

All Exhibits are listed in the Exhibit Index at the end of this Part II.

Item 9.  Undertakings

(a) The undersigned registrant hereby undertakes:

    (1) To file,  during any period in which  offers or sales are being made,  a
        post-effective amendment to this registration statement:

        (i) To  include  any  prospectus  required  by Section  10(a)(3)  of the
            Securities Act of 1933;

       (ii) To reflect in the  prospectus  any fact or events  arising after the
            effective  date of the  registration  statement  (or the most recent
            post-effective  amendment  thereof)  which,  individually  or in the
            aggregate,  represents a fundamental  change in the  information set
            forth in the registration statement;

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      (iii) To include  any  material  information  with  respect to the plan of
            distribution not previously disclosed in the registration  statement
            or any  material  change  to such  information  in the  registration
            statement;

        Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply
        if the  registration  statement  is on  Form  S-3 or Form  S-8,  and the
        information  required to be included in a  post-effective  amendment  by
        those   paragraphs  is  contained  in  periodic  reports  filed  by  the
        registrant  pursuant  to Section 13 or Section  15(d) of the  Securities
        Exchange  Act  of  1934  that  are  incorporated  by  reference  in  the
        registration statement.

    (2) That, for the purpose of determining  any liability under the Securities
        Act of 1933, each such post-effective  amendment shall be deemed to be a
        new registration  statement  relating to the securities offered therein,
        and the offering of such  securities  at that time shall be deemed to be
        the initial bona fide offering thereof.

    (3) To remove from  registration by means of a post-effective  amendment any
        of  the  securities   being   registered  which  remain  unsold  at  the
        termination of the offering.

(b) The  undersigned   registrant   hereby  undertakes  that,  for  purposes  of
    determining  any liability  under the Securities Act of 1933, each filing of
    the registrant's annual report pursuant to Section 13(a) or Section 15(d) of
    the Securities Exchange Act of 1934, (and, where applicable,  each filing of
    an employee  benefit  plan's annual report  pursuant to Section 15(d) of the
    Securities  Exchange Act of 1934) that is  incorporated  by reference in the
    registration  statement shall be deemed to be a new  registration  statement
    relating  to the  securities  offered  therein,  and  the  offering  of such
    securities at that time shall be deemed to be the initial bona fide offering
    thereof.

(c) Insofar as indemnification  for liabilities arising under the Securities Act
    of 1933 may be permitted to directors,  officers and controlling  persons of
    the  registrant  pursuant to the foregoing  provisions,  or  otherwise,  the
    registrant  has been  advised  that in the  opinion  of the  Securities  and
    Exchange  Commission  such  indemnification  is  against  public  policy  as
    expressed in the Act and is, therefore,  unenforceable.  In the event that a
    claim for  indemnification  against such liabilities (other than the payment
    by the  registrant  of expenses  incurred or paid by a director,  officer or
    controlling  person  of the  registrant  in the  successful  defense  of any
    action,  suit or  proceeding)  is  asserted  by such  director,  officer  or
    controlling  person in connection with the securities being registered,  the
    registrant  will,  unless in the  opinion of its counsel the matter has been
    settled  by  controlling  precedent,   submit  to  a  court  of  appropriate
    jurisdiction  the  question  whether such  indemnification  by it is against
    public  policy as  expressed  in the Act and will be  governed  by the final
    adjudication of such issue.

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                                   SIGNATURES
                                   ----------

The Registrant.  Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this registration
statement  to be  signed  on its  behalf  by  the  undersigned,  thereunto  duly
authorized, in the City of Memphis and State of Tennessee, on April 25, 2005.


FIRST HORIZON NATIONAL CORPORATION


By: /s/Marlin L. Mosby, III
    -----------------------
       Marlin L. Mosby, III
       Executive Vice President and
       Chief Financial Officer


Pursuant to the  requirements of the Securities Act of 1933,  this  registration
statement has been signed by the following  persons in the capacities and on the
date indicated.

Signature                 Title                         Date
----------------------    ---------------------         --------------

J.  Kenneth  Glass*       Chairman  of the Board,       April 25,  2005 
J.  Kenneth  Glass        President, Chief Executive
                          Officer and a Director
                          (principal executive officer)

Marlin L. Mosby, III*     Executive Vice President      April 25, 2005
Marlin L. Mosby, III      and Chief Financial Officer
                          (principal financial officer)

James F. Keen*            Executive Vice President      April 25, 2005
James F. Keen             and Corporate Controller
                          (principal accounting officer)

Robert C. Blattberg*      Director                      April 25, 2005
Robert C. Blattberg

Simon F. Cooper*          Director                      April 25, 2005
Simon F. Cooper

James A. Haslam, III*     Director                      April 25, 2005
James A. Haslam, III

R. Brad Martin*           Director                      April 25, 2005
R. Brad Martin

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Vicki R. Palmer*          Director                      April 25, 2005
Vicki R. Palmer

Michael D. Rose*          Director                      April 25, 2005
Michael D. Rose

Mary F. Sammons*          Director                      April 25, 2005
Mary F. Sammons

William B. Sansom*        Director                      April 25, 2005
William B. Sansom

Jonathan P. Ward*         Director                      April 25, 2005
Jonathan P. Ward

Luke Yancy III*           Director                      April 25, 2005
Luke Yancy III



*By: /s/Clyde A. Billings, Jr.
     -------------------------
        Clyde A. Billings, Jr.
        Attorney-in-Fact
        April 25, 2005

                                       5


                                  EXHIBIT INDEX
                                  -------------


Exhibit 4.1
Amended  and  Restated  Charter  of  the  Corporation,  incorporated  herein  by
reference to Exhibit 3(i) to the Corporation's Quarterly Report on Form 10-Q for
the quarter ended 3-31-04.

Exhibit 4.2
Bylaws of the Corporation,  as amended and restated as of 1-18-05,  incorporated
herein by reference to Exhibit 3.2 to the  Corporation's  Annual  Report on Form
10-K for the year ended December 31, 2004.

Exhibit 4.3
First Horizon Nonqualified  Deferred  Compensation Plan,  incorporated herein by
reference to Exhibit 4(c) to the  Corporation's  registration  statement on Form
S-8, Reg. No. 333-106015, filed June 11, 2003.

Exhibit 5.1
Opinion and consent of Clyde A.  Billings,  Jr.  concerning  the legality of the
securities being registered hereunder.

Exhibit 23.1
Consent of Independent Accountants.

Exhibit 24.1
Power of Attorney executed by certain directors and officers of the Registrant.

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