April 10, 2019

Yujiro Hata
President and Chief Executive Officer
IDEAYA Biosciences, Inc.
7000 Shoreline Court, Suite 350
South San Francisco, California 94080

       Re: IDEAYA Biosciences, Inc.
           Amendment No. 2 to Draft Registration Statement on Form S-1
           Submitted April 4, 2019
           CIK No. 0001676725

Dear Mr. Hata:

      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. 2 to Draft Registration Statement on Form S-1

Business
Summary of Clinical Data - Metastatic Uveal Melanoma, page 110

1.     We note you have concluded that certain patients experienced a clinical
benefit from the
       administration of IDE196 in the Phase 1 clinical trial for metastatic
uveal melanomahas.
       Please disclose the endpoints for the study and to what extent to
endpoints have been met.
2.     It appears from disclosure on page 115 that there were drug-related
serious adverse events
       in the Phase 1 clinical study of IDE196. Please expand your disclosure
to describe the
       serious adverse events experienced in ongoing trials for IDE196 and how
many were
       observed.
 Yujiro Hata
IDEAYA Biosciences, Inc.
April 10, 2019
Page 2

       You may contact Jorge Bonilla at (202) 551-3414 or Mark Rakip at (202)
551-3573 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Liz Walsh at (202) 551-3696 or Chris Edwards at (202) 551-6761 with any
other
questions.



                                                          Sincerely,
FirstName LastNameYujiro Hata
                                                          Division of
Corporation Finance
Comapany NameIDEAYA Biosciences, Inc.
                                                          Office of Healthcare
& Insurance
April 10, 2019 Page 2
cc:       Mark Roeder
FirstName LastName