Mailstop 3561
                                                           September 25, 2018

Via E-mail
Helmy Eltoukhy
Chief Executive Officer
Guardant Health, Inc.
505 Penobscot Dr.
Redwood City, California 94063

       Re:      Guardant Health, Inc.
                Amendment No. 2 to Registration Statement on Form S-1
                Filed September 21, 2018
                File No. 333-227206

Dear Mr. Eltoukhy:

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

       Please respond to this letter by amending your registration statement
and providing the
requested information. If you do not believe our comment applies to your facts
and
circumstances or do not believe an amendment is appropriate, please tell us why
in your
response.

       After reviewing any amendment to your registration statement and the
information you
provide in response to this comment, we may have additional comments. Unless we
note
otherwise, our references to prior comments are to comments in our September
21, 2018 letter.

Provisions in our corporate charter documents and under Delaware law...., page
54

Amended and restated certificate of incorporation and amended and restated
bylaws, page 167

1.     We note your response to prior comment 1 regarding your forum selection
provision that
       identifies the Court of Chancery of the State of Delaware as the
exclusive forum for
       certain litigation. However, it is not clear from your revised
disclosure whether this
       provision applies to actions arising under the Exchange Act. In that
regard, we note that
       your revised disclosure appears to be provided only as an example that a
court could find
       your choice of forum provision to be inapplicable or unenforceable.
Please revise your
       disclosure to clarify whether your exclusive forum provision would
require actions
       arising under the Exchange Act to be dismissed by the Court of Chancery
of the State of
       Delaware before they could be brought in federal court. As noted in
prior comment 1,
 Helmy Eltoukhy
Guardant Health, Inc.
September 25, 2018
Page 2

        Section 27 of the Exchange Act creates exclusive federal jurisdiction
over all suits
        brought to enforce any duty or liability created by the Exchange Act or
the rules and
        regulations thereunder. If this provision does not apply to actions
arising under the
        Exchange Act, please also ensure that the exclusive forum provision in
your certificate of
        incorporation states this clearly.

       You may contact Linda Cvrkel at (202) 551-3813 or Rufus Decker at (202)
551-3769 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Michael Killoy at (202) 551-7576 or Brigitte Lippmann at (202) 551-3713
with any other
questions.


                                                            Sincerely,

                                                            /s/ Brigitte
Lippmann (for)

                                                            John Reynolds
                                                            Assistant Director
                                                            Office of
Beverages, Apparel,
                                                            and Mining

cc:     B. Shayne Kennedy
        Latham & Watkins LLP