April 3, 2025

Stephen Williamson
Chief Financial Officer
Thermo Fisher Scientific Inc.
168 Third Avenue
Waltham , Massachusetts 02451

       Re: Thermo Fisher Scientific Inc.
           Form 10-K for the fiscal year ended December 31, 2024
           File No. 001-08002
Dear Stephen Williamson:

       We have limited our review of your filing to the financial statements
and related
disclosures and have the following comments.

       Please respond to this letter within ten business days by providing the
requested
information or advise us as soon as possible when you will respond. If you do
not believe a
comment applies to your facts and circumstances, please tell us why in your
response.

       After reviewing your response to this letter, we may have additional
comments.

Form 10-K For the fiscal year ended December 31, 2024
Item 7. Management's Discussion and Analysis of Financial Condition and Results
of
Operations
Segment Results, page 21

1.     Please expand your discussion of segment results to include additional
material
       information as described in Item 303 of Regulation S-K for each of your
segments.
       For example, please expand your discussion of the very strong growth in
the electron
       microscopy business and declines in the other instrumentation businesses
to include
       additional fact specific insight describing the reasons for the growth
and declines in
       the businesses, as well as related quantitative information. Please
provide us any
       proposed disclosure for future filings.
 April 3, 2025
Page 2
Item 8. Financial Statements
Disaggregated Revenues, page 53

2.     Please tell us how you applied the guidance in ASC 606-10-55-89 through
55-91
       when selecting the categories to use to disaggregate revenues. As part
of your
       response, please address how you considered disclosure of revenue
attributable to the
       primary / key businesses identified on pages 3 and 4. In this regard, we
also note your
       use of pie charts to reflect the revenues attributable to these
businesses in your 2024
       Investor Day presentation. In addition, please tell us how you
considered ASC 280-
       10-50-40 as it relates to your segment disclosures.

        In closing, we remind you that the company and its management are
responsible for
the accuracy and adequacy of their disclosures, notwithstanding any review,
comments,
action or absence of action by the staff.

       Please contact Kristin Lochhead at 202-551-3664 or Michael Fay at
202-551-3812
with any questions.



                                                            Sincerely,

                                                            Division of
Corporation Finance
                                                            Office of
Industrial Applications and
                                                            Services