SecProbe.io

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Mail Stop 4-06

      October 20, 2005

Paul Brauneis
Chief Financial Officer
Avici Systems, Inc.
101 Billerica Avenue
North Billerica, MA  01862

	Re:	Avici Systems, Inc.
      Form 10-K for the Fiscal Year Ended December 31, 2004
Forms 10-Q for Fiscal Quarters Ended March 31, 2005 and
June 30, 2005
      File No. 000-30865

Dear Mr. Brauneis:

      We have reviewed your response letter dated September 16,
2005
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 on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter.

Prior Comment no. 7 - Form 8-K dated July 21, 2005

1. We note your response to our previous comment no. 7 where you
indicate that non-GAAP measures provide information which may
negatively or positively affect the Company`s cash position and
liquidity.  Your further indicate that the purpose is to identify
those transactions which may not be indicative of future cash
flows.
Your arguments to support the use of non-GAAP measures appear to
imply that Management uses these non-GAAP measures as a measure of
liquidity.  Clarify why you have reconciled the non-GAAP measure
to
net loss and not to operating cash flows.  A reconciliation to net
loss appears to imply that you are presenting this measure as a
performance measure and yet your discussion as to the usefulness
of
such measures implies otherwise. Also, revise your future filings
to
include an enhanced discussion of why management believes the non-
GAAP financial measures provide useful information as indicated in
your response.

      As appropriate, please amend your filing and 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.  You
may wish to provide us with marked copies of any amendment to
expedite our review.  Please furnish a cover letter with any
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 any amendment and your responses to our comments.

	We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filing reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed 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.

      You may contact Megan Akst, Staff Accountant, at (202) 551-
3407
or me at (202) 551-3730 if you have questions regarding comments
on
the financial statements and related matters.

							Very truly yours,

							Kathleen Collins
      Accounting Branch Chief
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Paul Brauneis
Avici Systems, Inc.
October 20, 2005
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