Mail Stop 4561

      January 6, 2006

Tom Manley
Senior Vice President, Finance & Administration
and Chief Financial Officer
Cognos Inc.
3755 Riverside Drive
P.O. Box 9707, Station T
Ottawa, ON Canada  K1G 4K9

	Re:	Cognos Inc.
   Form 10-K for the Fiscal Year Ended
   February 28, 2005
		Filed April 29, 2005
   Form 10-Q for the fiscal quarter ended August 31, 2005
		File No. 033-72402

Dear Mr. Manley:

	We have reviewed your response to our letter dated November
17,
2005 in connection with our review of the above referenced filings
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 the Fiscal Year Ended February 28, 2005

Critical Accounting Estimates, page 44

1. Please refer to comment 1 in our letter dated November 17,
2005.
We have reviewed your response and note that product support
amounts
and/or stated renewal rates (expressed as a percentage of the
license
amount) that are included in arrangements are negotiated based on
your standard approved price lists which are within a
predetermined
range for similar customer classes.  Tell us your reasonable
percentage range for each class of customer, including the median
percentage in the range.  Additionally, tell us what percentage of
your customers, by class, fall within each range.

2. We also note that where the negotiated percentage is not
considered substantive, an additional portion of the arrangement
fee
is allocated to product support based on the reasonable range to
ensure the amount allocated to product support is consistent with
VSOE.  Clarify how you allocate amounts for product support when
the
negotiated percentage is outside the reasonable range.  In this
regard, tell us how you allocate product support amounts when the
negotiated percentage is above and below the reasonable range.

      * * * * *

      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.

	 You may contact Patrick Gilmore at (202) 551-3406 or me at
(202) 551-3730 if you have questions regarding comments on the
financial statements and related matters.

							Sincerely,


							Kathleen Collins
							Accounting Branch Chief

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Tom Manley
Cognos Inc.
January 6, 2006
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