EXHIBIT 24

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below does hereby constitute and appoint MARLIN L. MOSBY, III, JAMES F.
KEEN, CLYDE A. BILLINGS, JR., and MILTON A. GUTELIUS, JR., jointly and each of
them severally, his or her true and lawful attorney-in-fact and agent, with full
power of substitution and resubstitution, for him or her and in his or her name,
place and stead, in any and all capacities, to execute and sign the Annual
Report on Form 10-K for the fiscal year ended December 31, 2004 to be filed with
the Securities and Exchange Commission, pursuant to the provisions of the
Securities Exchange Act of 1934, by First Horizon National Corporation
("Corporation") and, further, to execute and sign any and all amendments thereto
and to file the same, with all exhibits thereto and other documents in
connection therewith, with the Securities and Exchange Commission, granting unto
said attorneys-in-fact and agents, and each of them, or their or his or her
substitute or substitutes, full power and authority to do and perform each and
every act and thing requisite or necessary to be done in and about the premises,
as fully to all intents and purposes as the undersigned might or could do in
person, hereby ratifying and confirming all the acts that said attorneys-in-fact
and agents, or any of them, or their or his or her substitute or substitutes,
may lawfully do or cause to be done by virtue hereof.

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

/s/ J. Kenneth Glass Chairman of the Board, President and March 4, 2005
- ---------------------------- Chief Executive Officer and a Director
J. Kenneth Glass (principal executive officer)

/s/ Marlin L. Mosby, III Executive Vice President and Chief March 4, 2005
- ---------------------------- Financial Officer (principal financial
Marlin L. Mosby, III officer)

/s/ James F. Keen Executive Vice President and Corporate March 4, 2005
- ---------------------------- Controller (principal accounting officer)
James F. Keen

/s/ Robert C. Blattberg Director March 4, 2005
- ----------------------------
Robert C. Blattberg

- ---------------------------- Director
George E. Cates

/s/ Simon F. Cooper Director March 4, 2005
- ----------------------------
Simon F. Cooper

/s/ James A. Haslam, III Director March 4, 2005
- ----------------------------
James A. Haslam, III

/s/ R. Brad Martin Director March 4, 2005
- ----------------------------
R. Brad Martin

/s/ Vicki R. Palmer Director March 4, 2005
- ----------------------------
Vicki R. Palmer

/s/ Michael D. Rose Director March 4, 2005
- ----------------------------
Michael D. Rose

/s/ Mary F. Sammons Director March 4, 2005
- ----------------------------
Mary F. Sammons

/s/ William B. Sansom Director March 4, 2005
- ----------------------------
William B. Sansom

/s/ Jonathon P. Ward Director March 4, 2005
- ----------------------------
Jonathan P. Ward

/s/ Luke Yancy III Director March 4, 2005
- ----------------------------
Luke Yancy III