Mail Stop 6010
February 21, 2006


Ms. Jessica M. Hoover
Vice President, Head of Corporate Business Development
Chiron Corporation
4560 Horton Street
Emeryville, California 94608

Re:	Chiron Corporation
   Revised Proxy Statement on Schedule 14A, Schedule 13E-3
   and all included and incorporated documents
   File No. 0-12798, Filed February 6, 2006

Dear Ms. Hoover:

      We have reviewed your filings and have the following
comments.
Where indicated, we think you should revise your documents 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
supplemental information so we may better understand your
disclosure.
After reviewing this information, we may or may not 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.

Background of the Merger, pages 4-10

1. Please revise your disclosure to briefly describe Pulminiq`s
approvable letter and Tifacogin`s failure to meet study endpoints
in
the OPTIMIST phase III trial.


2. We note your response to our prior comment 13 and reissue that
comment.  Item 1014(d) Regulation M-A requires you to state
"whether
or not a majority of directors . . . has retained an unaffiliated
representative to act solely on behalf of unaffiliated security
holders for purposes of negotiating the terms of the Rule 13e-3
transaction and/or preparing a report concerning the fairness of
the
transaction."  Your disclosure refers to how the member of the
board
retained independent legal counsel, Sullivan & Cromwell, and the
financial advisors, Credit Suisse and Morgan Stanley.  It appears
that Sullivan & Cromwell, Credit Suisse and Morgan Stanley were
retained for the board and not to act solely on behalf of
unaffiliated security holders.  Please revise your disclosure to
state that no one was retained to act solely on behalf of
unaffiliated security holders.


Position of the Novartis Entities Regarding Fairness of the
Merger,
pages 16-19

3. We note your response to our prior comment 21, in particular
your
description of "various human resources difficulties."  While you
discuss the diversion of key personnel on page 16, you no longer
mention "employee turnover" as a factor considered by Novartis.
Please confirm to us that this was not a factor as previously
disclosed, or revise your disclosure to describe.

4. We note the statement on page 17 that Novartis developed
detailed
projections for Chiron`s businesses.  Please revise to include
these
projections and any assumptions on which these projections are
based.

5. Revise to quantify and describe the anticipated synergies and
explain why Novartis factored 50% of the anticipated synergies.
Also, revise to disclose why Novartis and Goldman used a 10%
discount
rate and terminal value assumptions.

6. We note your response to our prior comments 23 and 24 and
reissue
those comments in part.  You have stated on page 17 that the cash
consideration represents a substantial premium to Chiron`s fair
trading value and noted that it is within the range of premiums
implied in similarly sized biotechnology transactions.
Additionally,
you state on page 18 that Goldman Sachs prepared analyses of
premiums
paid in transactions involving companies in Chiron`s industry and
going private transactions.  Please revise your disclosure to
identify:

* the transactions included in the analyses;
* the criteria used to select the transactions included in the
analyses;
* any transactions excluded from the analyses and the reason(s)
for
their exclusion; and
* the implied premiums in those transactions.


7. It appears that Novartis Entities relied upon the Goldman Sachs
discussion materials summarized on page 18 and filed as an exhibit
to
the Schedule 13E-3.  In this regard, it appears that the Novartis
Entities should expressly adopt the conclusion and analyses of
Goldman Sachs in order to fulfill its disclosure obligation Item
1014(b) and Instruction 2(iv).  Alternatively, revise to disclose
in
more detail the analyses performed by the Novartis Entities in
determining whether the consideration offered to unaffiliated
security holders constitutes fair value in relation to the going
concern value of Chiron.

8. You disclose on page 18 that in connection with the above-
described investment banking and other services Goldman Sachs has
received, and may receive, compensation.  Also, on page 19 you
disclose that Novartis has agreed to pay Goldman Sachs "customary
fees" for its services in connection with the engagement.  Please
revise to disclose the compensation received by Goldman Sachs
during
the past two years.  Also, revise to disclose the compensation to
be
received by Goldman Sachs as a result of this engagement.  See
Item
1015(b)(4) of Regulation M-A.

9. We note that in light of market valuation measures and the
nature
of Chiron`s business and assets, none of the Novartis entities
deemed
net book value or liquidation value to be relevant indicators of
the
value of the shares of Chiron`s common stock.  Please expand your
disclosure to explain why the market valuation measures and the
nature of Chiron`s business and assets deem net book value and
liquidation value irrelevant indicators of value.

Chiron Agreement with Schering AG Relating to Betaseron, page 19

10. We note your response to our prior comment 2 your disclosure
that
"Novartis did not assign a positive or negative value to the
existence of the clause in to its financial analysis."  Please
revise
your disclosure to explain if this clause had any other impact on
Novartis` decision.

Opinions of Chiron`s Financial Advisors, pages 20-29

11. We note your response to our prior comment 27 and reissue that
comment in part.  Please revise your disclosure to clearly explain
how the financial advisors used the P/E multiples of the
comparable
companies to determine the appropriate range of P/E multiples for
Chiron and how they used the mean and/or median.  We note your
revised disclosure of the mean and median, but it appears that the
financial advisors concluded that the P/E multiples of certain
companies, Amgen Inc., Biogen Idec Inc., Genzyme Corporation and
Gilead Sciences, Inc. , were the most relevant, and that the mean
and
median did not really impact their analysis.  Please clarify.
Additionally, please explain how the financial advisors used the
growth rates for each of the comparable companies.



12. We note your response to our prior comment 30.  Please revise
your disclosure to explain what you mean by "criteria intrinsic to
Chiron."  In addition, we note your statement that the precedent
transaction information was provided to the Chiron board.  If
Chiron`s board considered this supplemental information, it would
appear that it should be discussed in "Fairness of the Merger;
Recommendation of the Non-Novartis Directors of Chiron`s Board of
Directors."

13. We note your response to our prior comment 31 and reissue that
comment.  Your revised disclosure that Credit Suisse and Morgan
Stanley did not use the precedent transactions as part of their
valuation criteria does not respond to our prior comment.  Please
explain whether the Chiron Board considered the Glaxo Smith Kline
agreement to acquire ID Biomedical as a comparison in determining
whether the terms of the merger consideration were fair.  If they
did
consider this agreement, please revise to include a discussion.
If
they did not, please advise us accordingly.

Transactions and Relationships Between Novartis and Chiron, page37

Relationship with Novartis AG, page 37

14. We note your disclosure that Chiron and Novartis continue to
work
together on an arm`s-length basis while remaining independent to
pursue their respective corporate strategies.  As we noted in
prior
comment 16, it appears that the very nature of this transaction
and
Chiron`s relationship with Novartis precludes you from stating
that
Chiron and Novartis work together on an arm`s length basis.
Please
revise your disclosure to remove this reference.

Market Prices and Dividend Information, page 65

15. Please revise your disclosure to include the most recent
market
price practicable.

Where You Can Find More Information, pages 70-71

16. We note your response to our prior comment 32 and reissue that
comment.  Your reference to "as amended" is still present and
should
be removed as you did not amend any of your 2005 Forms 10-Q.


*    *    *    *

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

      You may contact Amy Bruckner at (202) 551-3657 or Mary Mast
at
(202) 551-3613 if you have questions regarding comments on the
financial statements and related matters.  Please contact Sonia
Barros at (202) 551-3655, or Suzanne Hayes at (202) 551-3675 with
any
other questions.

  Sincerely,



									Jeffrey Riedler
									Assistant Director

cc:	Alison S. Ressler, Esq.
Patrick S. Brown, Esq.
Sullivan & Cromwell LLP
1888 Century Park East, Suite 2100
Los Angeles, California 90067-1725



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Ms. Jessica M. Hoover
Page 5