United States securities and exchange commission logo





                             September 7, 2023

       Ken Song, M.D.
       President and Chief Executive Officer
       RayzeBio, Inc.
       5505 Morehouse Drive, Suite 300
       San Diego, CA 92121

                                                        Re: RayzeBio, Inc.
                                                            Registration
Statement on Form S-1
                                                            Response dated
September 1, 2023
                                                            File No. 333-274193

       Dear Ken Song:

              We have reviewed your 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.

       Registration Statement on Form S-1, filed August 24, 2023

       Management's Discussion and Analysis of Financial Condition and Results
of Operations
       Stock-based Compensation Expense, page 114

   1.                                                   Revise your table on
page 116, and elsewhere in the filing as appropriate, to address your
                                                        stock options granted
August 22, 2023.
 Ken Song, M.D.
FirstName LastNameKen Song, M.D.
RayzeBio, Inc.
Comapany 7,
September NameRayzeBio,
             2023        Inc.
September
Page 2    7, 2023 Page 2
FirstName LastName
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

       Refer to Rules 460 and 461 regarding requests for acceleration. Please
allow adequate
time for us to review any amendment prior to the requested effective date of
the registration
statement.

       You may contact Gary Newberry at 202-551-3761 or Kevin Vaughn at
202-551-3494 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Joshua Gorsky at 202-551-7836 or Margaret Schwartz at 202-551-7153 with
any other
questions.



                                                           Sincerely,

                                                           Division of
Corporation Finance
                                                           Office of Life
Sciences
cc:      Terren J. O'Connor, Esq.