June 6, 2019

Christopher Peetz
Chief Executive Officer
Mirum Pharmaceuticals, Inc.
950 Tower Lane, Suite 1050
Foster City, CA 94404

       Re: Mirum Pharmaceuticals, Inc.
           Amendment No. 1 to Draft Registration Statement on Form S-1
           Submitted May 24, 2019
           CIK No. 0001759425

Dear Mr. Peetz:

      We have reviewed your amended draft registration statement and have the
comments. In some of our comments, we may ask you to provide us with
information so we
may better understand your disclosure.

       Please respond to this letter by providing the requested information and
either submitting
an amended draft registration statement or publicly filing your registration
statement on
EDGAR. If you do not believe our comments apply to your facts and circumstances
or do not
believe an amendment is appropriate, please tell us why in your response.

      After reviewing the information you provide in response to these comments
and your
amended draft registration statement or filed registration statement, we may
have additional
comments. Unless we note otherwise, our references to prior comments are to
comments in our
May 16, 2019 letter.

Amendment No. 1 to Draft Registration Statement on Form S-1

Our Clinical Trials of Maralixibat in PFIC
Phase 2 INDIGO Trial, page 96

1.     We note your response to prior comment 13. Please clarify the narrative
discussion here
       to explain whether the secondary endpoint for pruritus was met.
Principal Stockholders, page 150

2.     We note your revised disclosures in the table, but certain of the
footnotes do not appear to
       contain corresponding disclosure. Please reconcile or advise.
 Christopher Peetz
Mirum Pharmaceuticals, Inc.
June 6, 2019
Page 2

       You may contact Paul Cline at 202-551-3851 or Angela Connell at
202-551-3426 if you
have questions regarding comments on the financial statements and related
matters. Please
contact Dorrie Yale at 202-551-8776 or Mary Beth Breslin at 202-551-3625 with
any other

FirstName LastNameChristopher Peetz
                                                        Division of Corporation
Comapany NameMirum Pharmaceuticals, Inc.
                                                        Office of Healthcare &
June 6, 2019 Page 2
cc:       Jason L. Kent - Cooley LLP
FirstName LastName