Mail Stop 6010


	October 27, 2006


Valentin P. Gapontsev, Ph.D.
Chief Executive Officer and Chairman of the Board
IPG Photonics Corporation
50 Old Webster Road
Oxford, Massachusetts  01540

      Re:	IPG Photonics Corporation
      Amendment No. 2 to Registration Statement on Form S-1
      Filed on October 18, 2006
		File No. 333-136521

Dear Dr. Gapontsev:

      We have reviewed your filing and have the following
comments.
Where indicated, we think you should revise your document in
response
to these comments.  If you disagree, we will consider your
explanation as to why our comment is inapplicable or a revision is
unnecessary.  Please be as detailed as necessary in your
explanation.
In some of our comments, we may ask you to provide us with
information so we may better understand your disclosure.  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.

We are subject to various environmental laws, page 16

1. Please reconcile your disclosure that compliance with current
laws
could cause you to incur significant expenses with your response
to
prior comment 3 that you are not aware of material non-compliance
with current laws.

Series B Preferred Stockholders, page 85

2. We note your response to prior comment 16 of our letter dated
October 10, 2006 letter and comment 54 of our letter dated
September
7, 2006.  With a view toward clarified disclosure of the effect of
the December 2005 amendment, please tell us what the series B
preferred stockholders would have received in a qualified public
offering of $25.00 per share both before and after the amendment.

Series D Preferred Stockholder, page 87

3. We note from your response to prior comment 17 that the
conversion
rate under the Series D preferred stock was changed upon the
repayment of the convertible note, resulting in a change to the
number of common shares issuable upon conversion of the Series D
preferred stock.  Please clarify where you have provided the
updated
disclosure you have mentioned in your response.

4. From your response to prior comment 18, it is unclear how you
have
"not purchased any semiconductor diodes from JDSU" given your
disclosure in that same paragraph that you are required to
purchase a
percentage of this "key component" from JDSU.  Please clarify.

*  *  *  *  *
      As appropriate, please amend your registration statement in
response to these comments.  You may wish to provide us with
marked
copies of the amendment to expedite our review.  Please furnish a
cover letter with your amendment that keys your responses to our
comments and provides any requested information.  Detailed cover
letters greatly facilitate our review.  Please understand that we
may
have additional comments after reviewing your amendment and
responses
to our comments.

      We direct your attention to Rules 460 and 461 regarding
requesting acceleration of a registration statement.  Please allow
adequate time after the filing of any amendment for further review
before submitting a request for acceleration.  Please provide this
request at least two business days in advance of the requested
effective date.

	You may contact Eric Atallah at (202) 551-3663 or Jay Webb at
(202) 551-3603 if you have questions regarding comments on the
financial statements and related matters.  Please contact Tim
Buchmiller at (202) 551-3635 or me at (202) 551-3617 with any
other
questions.

      					Sincerely,



      					Russell Mancuso
      					Branch Chief

cc (via fax): 	Robert W. Ericson, Esq.
		David A. Sakowitz, Esq.
Valentin P. Gapontsev, Ph.D.
IPG Photonics Corporation
October 27, 2006
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