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                             December 5, 2023

       James Frates
       Chief Financial Officer
       Amylyx Pharmaceuticals, Inc.
       43 Thorndike St.
       Cambridge, MA 02141

                                                        Re: Amylyx
Pharmaceuticals, Inc.
                                                            Form 10-K for the
Fiscal Year Ended December 31, 2022
                                                            Filed March 13,
2023
                                                            Form 10-Q for the
Quarterly Period Ended September 30, 2023
                                                            Filed November 9,
2023
                                                            File Number
001-41199

       Dear James Frates:

              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-Q for the Nine Months Ended September 30, 2023

       Notes to Condensed Consolidated Financial Statements
       3. Product Revenue, Net, page 10

   1.                                                   Please tell us your
consideration of providing disaggregated revenue disclosure such as
                                                        product sales for the
U.S. and Canada. Refer to ASC 606-10-55-89 through 606-10-55-91
                                                        and ASC 280-10-50-41.
       Notes to the Condensed Consolidated Financial Statements
       5. Inventories, page 12

   2.                                                   Your inventory balance
was $56.7 million at September 30, 2023, of which $24.3 million
                                                        is considered
long-term. You state that finished goods have a shelf life of 12 - 18 months
                                                        from the date of
manufacture. Tell us how much of the long-term inventory is
 James Frates
Amylyx Pharmaceuticals, Inc.
December 5, 2023
Page 2
         considered finished goods. In light of the shelf life, the early phase
of the company's
         product sale launch, and a significant portion of inventories being
recorded as long-term,
         tell us why you believe no impairment was required to be recorded at
September 30, 2023.
       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 Mary Mast at 202-551-3613 or Angela Connell at
202-551-3426 with any
questions.



FirstName LastNameJames Frates                               Sincerely,
Comapany NameAmylyx Pharmaceuticals, Inc.
                                                             Division of
Corporation Finance
December 5, 2023 Page 2                                      Office of Life
Sciences
FirstName LastName