SecProbe.io

<DOCUMENT>
<TYPE>LETTER
<SEQUENCE>1
<FILENAME>filename1.txt
<TEXT>

								September 30, 2005

Mail Stop 6010

Jeffrey H. Burbank
President and Chief Executive Officer
NxStage Medical, Inc.
439 South Union Street, 5th Floor
Lawrence, Massachusetts 01843

      Re:	NxStage Medical, Inc.
      Amendment No. 1 to Registration Statement on Form S-1
      Filed September 21, 2005
		File No. 333-126711

Dear Mr. Burbank:

      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.

      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.

Amendment No. 1 to Form S-1
1. We note your response to comment 1; however, we continue to
notice
blanks in your document, like those on pages 82, 84 and 99.
Please
provide all required information.

Artwork
2. In an appropriate section of your document, please clarify the
portion of your business derived from the uses mentioned on the
front
cover artwork versus the back cover artwork.  Also tell us how
your
placement of the artwork objectively represents this contribution.

Summary, page 1
3. We note your response to comment 4.  Please tell us how the
materials you submitted support the disclosure that 8% of U.S.
ERSD
dialysis patients receive some form of dialysis treatment at home.
The information provided in tab 1 of Annex A seems to indicate
that
"home hemodialysis" comprised a percentage less than 8%.
4. Please expand your response to comment 5 to tell us where the
clinics are located.

5. With a view toward disclosure, please tell us how you
determined
the size of the reverse split.

We currently have obligations, page 16

6. Please revise your disclosure in response to comment 9 to
clarify
how your business would give you access to confidential patient
information.

Management`s Discussion and Analysis of Financial Condition and
Results of Operation, page 33
7. We note your disclosure in response to comment 2 that you
organized NxStage Verwaltungs GmbH in July 2005.  Disclose your
business purpose for organizing this entity and what the nature of
its operations will be once it commences conducting business.

Business, page 50

Market Opportunity, page 51

8. We note the materials provided in tab 4 of Annex C in response
to
comment 20.  Please disclose which data in your prospectus is
based
on your own studies versus independent, objective studies.

9. Please expand your response to comment 21 to tell us the form
of
the compensation you pay.

10. We note your reference to Annex D in response to comment 22.
Please provide us with Annex D, as it appears it was not submitted
with the other annexes.
Designed for safety, page 57

11. We note your response to comment 23.  Your response does not
address your experience with operator error.  Please tell us your
experience with operator error and whether there have been any
related material consequences to patients.

Underwriting, page 106

12. Please expand your response to comment 33 to clarify that (1)
the
staff of the Office of Chief Counsel has reviewed and cleared both
the procedures and all communications used in both the i-Deal and
IPO
Center systems, and (2) the procedures and communications to be
used
in the offering are the same as those previously reviewed and
cleared
for those two systems.  If you are unable to make this
representation, please provide us with all the i-Deal and IPO
Center
system materials, including screen shots and the text of any
communications the underwriters propose to use in the electronic
distribution.  We may have additional comments upon review of
those
materials.

Other Relationships, page 109

13. Please expand your disclosure in response to comment 36 to
provide more specific disclosure about the services that the
underwriters or their affiliates "have provided."  Include
information about any future compensation arrangements for these
or
other services.

Consolidated Financial Statements, page F-1

Consolidated Statements of Cash Flows, page F-6

14. Please refer to our prior comment 38.  From your response we
note
that the transfers between inventory and field equipment represent
non-cash transfers.  As such, based upon the information you
provided
in your response, please revise to reflect these non-cash
transfers
in accordance with paragraph 32 of SFAS 95.  In the alternative,
explain to us why these transfers represent cash transactions that
should be reflected within your cash used in or provided by
operating
and financing activities.

Note 2. Summary of Significant Accounting Policies, page F-7

Revenue Recognition, page F-10

15. We refer to our prior comment 43.  Please tell us and disclose
whether you have any refund or similar obligations to your
customers
if they fail to fulfill the minimum purchase requirements.  Please
tell us and disclose whether you cease depreciating the equipment
once the customer has met the minimum purchase requirement.
Please
tell us why you classify these units within inventory and not
within
field equipment.  Also, since you are recognizing the cost of
sales
on a straight-line basis, but record revenue sporadically as
disposables are purchased, please tell us your consideration of
why
the straight-line basis of cost recognition is appropriate.

Note 6. Redeemable Preferred Stock and Stockholders` Equity
(Deficit), page F-17

Conversion, page F-18

16. We refer to our prior comment 47.  We see your conclusion that
there was no beneficial conversion feature at the commitment date.
Please tell us how you considered EITF 98-5 and 00-27 in reaching
this conclusion.  Also discuss how you will measure the amount to
recognize as a dividend upon completion of the initial public
offering.

Note 7. Stock Options, page F-19

17. We refer to our prior comment 48. We note your reference to
valuations prepared retrospectively by an independent valuation
specialist to reassess the fair value of your common stock as of
each
of the option grant dates. Please note that if you elect to
continue
to make such a reference you should identify the appraisal firm
under
"Experts" and include their consent in the registration statement.
Alternatively, we encourage you to clearly disclose that
management
is primarily responsible for estimating fair value.  We will not
object if you wish to state, in revised disclosure, that
management
considered a number of factors, including valuations or
appraisals,
when estimating fair value.  Regardless of your decision, your
disclosure should clearly indicate that management is responsible
for
the valuation.

      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 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 Act
of
1933 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.

      We will consider a written request for acceleration of the
effective date of the registration statement as confirmation of
the
fact that those requesting acceleration are aware of their
respective
responsibilities under the Securities Act of 1933 and the
Securities
Exchange Act of 1934 as they relate to the proposed public
offering
of the securities specified in the above registration statement.
We
will act on the request and, pursuant to delegated authority,
grant
acceleration of the effective date.

      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 Julie Sherman at (202) 551-3640 or Kaitlin
Tillan at (202) 551-3604 if you have questions regarding comments
on
the financial statements and related matters.  Please contact
Eduardo
Aleman at (202) 551-3646 or me at (202) 551-3617 with any other
questions.

      					Sincerely,

      					Russell Mancuso
      Branch Chief

cc(via facsimile) Mark. G. Borden, Esq.
??

??

??

??

Jeffrey H. Burbank
NxStage Medical, Inc.
September 30, 2005
Page 1

</TEXT>
</DOCUMENT>