Mailstop 3561
                                                              September 21,
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. 1 to Registration Statement on Form S-1
                Filed September 18, 2018
                File No. 333-227206

Dear Mr. Eltoukhy:

      We have reviewed your amended 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 amending your registration statement
and providing the
requested information. 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 any amendment to your registration statement and the
information you
provide in response to these comments, we may have additional comments.

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 that your forum selection provision identifies the Court of
Chancery of the State
       of Delaware as the exclusive forum for certain litigation, including any
"derivative
       action." Please disclose whether this provision applies to actions
arising under the
       Exchange Act. In that regard, we note that 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.

2.     We note that in the tenth clause of your amended and restated
certificate of incorporation
       filed as exhibit 3.2, you include a proviso for subject matter
jurisdiction in the exclusive
       state forum provision. Please describe this proviso in the filing.
 Helmy Eltoukhy
Guardant Health, Inc.
September 21, 2018
Page 2

       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