EXHIBIT 5


                                       September 20, 2005




ESCO Technologies Inc.
9900A Clayton Road
St. Louis, MO  63124-1186

Ladies and Gentlemen:

     I am Assistant Secretary and Associate General Counsel of ESCO Technologies
Inc., a Missouri corporation (the "Company"), and in such capacity I am familiar
with the  Post-Effective  Amendment No. 1 to the Registration  Statement on Form
S-8 (the  "Post-Effective  Amendment")  relating  to the  Company's  2001  Stock
Incentive Plan and 2004 Incentive  Compensation Plan (the "Plans") to which this
letter is filed as an exhibit. The Post-Effective  Amendment registers 2,105,365
shares of the  Company's  common  stock,  par value $0.01 per share (the "Common
Stock"),   offered  pursuant  to  stock  options,   stock  appreciation  rights,
performance share awards,  restricted stock awards and other stock-based awards,
granted and which may be granted under the Plans,  including the Preferred Stock
Purchase  Rights  associated  with such Common  Stock (the Common  Stock and its
associated Preferred Stock Purchase Rights, the "Securities").

     I have examined originals or copies,  certified or otherwise  identified to
my satisfaction,  of such documents,  corporate records,  certificates of public
officials  and other  instruments  as I deemed  necessary for the purpose of the
opinion expressed herein.

     On the basis of the  foregoing,  I am of the opinion  that the  Securities,
when sold or distributed in accordance with the provisions of the Plans, will be
legally issued, fully paid and non-assessable.

     I consent to the filing of this letter as an exhibit to the  Post-Effective
Amendment.

                                                    Very truly yours,


                                                    /s/ Thomas B. Martin_____
                                                    Thomas B. Martin

TBM/bjo

Enclosures