June 20, 2006

Room 7010

David A. Martin
Principal Financial and Accounting Officer
Insituform Technologies, Inc.
702 Spirit 40 Park Drive
Chesterfield, Missouri 63005

Re:	Insituform Technologies, Inc.
	Form 10-K for Fiscal Year Ended December 31, 2005
Forms 10-Q for the Fiscal Quarter Ended March 31, 2006
	File No. 000-10786

Dear Mr. Martin:

      We have reviewed the above referenced filing and have the
following comments.  Please note that we have limited our review
to
the matters addressed in the comments below.  We may ask you to
provide us with supplemental information so we may better
understand
your disclosure.  Please be as detailed as necessary in your
explanation.  After reviewing this information, we may raise
additional comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or any other aspect
of
our review.  Feel free to call us at the telephone numbers listed
at
the end of this letter.

Form 10-K for Fiscal Year Ended December 31, 2005

Note 14. Segment and Geographic Information, page 64

1. We note during 2004 and 2005 your tunneling segment experienced
margin deterioration and that your backlog has been decreasing of
the
past couple of years.  You disclose that this deterioration is a
result of losses on a project in Chicago and negative gross margin
adjustments on two other significant projects.  We further note
that
you had made "enhancements" to the internal controls related to
the
tunneling segment which included replacing some management
positions.
Considering the deteriorating condition of this segment and the
internal control changes you have made, please tell us the
following:

* How you determined it was appropriate to recognize revenue for
claims during 2005 and how your accounting of these claims
complies
with paragraphs 62 and 65 of SOP 81-1.   In this regard, tell us
whether or not these projects for which you are recording claim
income are any of the projects that have incurred significant
losses
during 2005, including the Chicago project.  If so, tell us how
you
were able to determine that the costs of this project are
recoverable
and revenue recognition for these change order/claims is
appropriate.
* How you determined that the Goodwill and long-lived assets
associated with the tunneling segment were recoverable and an
impairment charge was not necessary.
* Tell us how you considered the history of negative margins and
operating losses when disclosing any known trends or uncertainties
that you reasonably expect will have a material favorable or
unfavorable impact on operations.  Refer to Item 303 of Regulation
S-
K.

      As appropriate, please respond to these comments within 10
business days or tell us when you will provide us with a response.
Please submit all correspondence and supplemental materials on
EDGAR
as required by Rule 101 of Regulation S-T.  Detailed cover letters
greatly facilitate our review.  Please understand that we may have
additional comments after reviewing your responses to our comments

	 We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filing to be certain that the
filing includes all information required under the Securities
Exchange Act of 1934 and that they have provided all information
investors require for an informed investment decision.  Since the
company and its management are in possession of all facts relating
to
a company`s disclosure, they are responsible for the accuracy and
adequacy of the disclosures they have made.

	In connection with responding to our comments, please
provide,
in writing, a statement from the company acknowledging that:

* the company is responsible for the adequacy and accuracy of the
disclosure in the filing;

* staff comments or changes to disclosure in response to staff
comments do not foreclose the Commission from taking any action
with
respect to the filing; and

* the company may not assert staff comments as a defense in any
proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in our review of your filing or in
response to our comments on your filing.

	You may contact Melissa Rocha at (202) 551-3854 or me at
(202)
551-3689 if you have questions regarding comments on the financial
statements and related matters.


Sincerely,


John Hartz
Senior Assistant Chief Accountant

David A. Martin
Insituform Technologies, Inc.
June 20, 2006
Page 1


UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

         DIVISION OF
   CORPORATION FINANCE