November 27, 2018

Ben Silbert
General Counsel and Secretary
Avista Healthcare Public Acquisition Corp.
65 East 55th Street
18th Floor
New York, NY 10022

       Re: Avista Healthcare Public Acquisition Corp.
           Amendment No. 3 to Registration Statement on Form S-4
           Filed November 19, 2018
           File No. 333-227090

Dear Mr. Silbert:

      We have reviewed your amended draft registration statement and have the
following
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.

Amendment No. 3 to Registration Statement on Form S-4 filed on November 19,
2018

Material Tax Considerations, page 115

1.     We note the disclosure that Weil, Gotshal & Manges LLP's opinion is that
the
       domestication "should" qualify as a reorganization within the meaning of
Section
       368(a)(1)(F). Additionally, we note the lack of authority directly
addressing the
       domestication. Please expand the discussion to further explain the facts
or circumstances
       resulting in this uncertainty. For example, does the business
combination raise any doubts
       that the domestication qualifies as a reorganization within the meaning
of Section
       368(a)(1)(F)? Refer to Staff Legal Bulletin No. 19 Section III.C.4.
2.     Please revise your disclosure regarding he material Cayman Islands tax
considerations
 Ben Silbert
Avista Healthcare Public Acquisition Corp.
November 27, 2018
Page 2
      to provide the opinion as to the "material" Cayman Islands income tax
consequences,
      rather than "a general summary" of "certain" consequences. Please refer
to Staff Legal
      Bulletin No. 19 Section III.C.1.
Exhibits

3.    Please file a revised tax opinion from Cayman Islands counsel that states
the relevant
      disclosure in the registration statement constitutes the opinion of
counsel. Refer to Section
      III.B.2 of Staff Legal Bulletin No. 19. Additionally, please file the
signed opinion of
      counsel regarding the tax consequences of the domestication.
       You may contact Keira Nakada at 202-551-3659 or Kevin Vaughn at
202-551-3494 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Christine Westbrook at 202-551-5019 or Suzanne Hayes at 202-551-3675
with any other
questions.



                                                            Sincerely,
FirstName LastNameBen Silbert
                                                      Division of Corporation
Finance
Comapany NameAvista Healthcare Public Acquisition Corp.
                                                      Office of Healthcare &
Insurance
November 27, 2018 Page 2
cc:       Jackie Cohen, Esq.
FirstName LastName