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                            April 30, 2020

       Sarah Boyce
       President and Chief Executive Officer
       Avidity Biosciences, Inc.
       10975 N. Torrey Pines Road, Suite 150
       La Jolla, California 92037

                                                        Re: Avidity
Biosciences, Inc.
                                                            Draft Registration
Statement on Form S-1
                                                            Submitted April 3,
2020
                                                            CIK No. 0001599901

       Dear Ms. Boyce:

              We have reviewed your 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.

       Draft Registration Statement on Form S-1

       Our Development Programs, page 2

   1.                                                   We note that you have
four muscle programs in the research and discovery stage. Please
                                                        provide us your
analysis as to why these programs are material enough to be included in
                                                        your pipeline table.
Please also add columns for each of Phase 1, Phase 2 and Phase 3 to
                                                        the table.
   2.                                                   Please revise to
explain what you mean by "durable, dose-dependent manner" as used in
                                                        the second paragraph on
page 3 and elsewhere in the prospectus.
 Sarah Boyce
FirstName LastNameSarah Boyce
Avidity Biosciences, Inc.
Comapany NameAvidity Biosciences, Inc.
April 30, 2020
Page 30,
April 2 2020 Page 2
FirstName LastName
Our Strategy, page 4

3.       We note your disclosure that your strategy is to "rapidly advance" or
"rapidly progress"
         clinical development for some of your muscle programs. Please revise
these statements
         and any similar disclosure to remove any implication that you will be
successful in
         commercializing your product candidates in a rapid or accelerated
manner as such
         statements are speculative. In addition, please identify the
development pathways you
         intend to pursue to expedite approval of your lead candidate, should
your Phase 1/2 trial
         of AOC 1001 planned for 2021 be successful as noted on page 3.
Implications of Being an Emerging Growth Company and a Smaller Reporting
Company, page 6

4.       Please supplementally provide us with copies of all written
communications, as defined in
         Rule 405 under the Securities Act, that you, or anyone authorized to
do so on your behalf,
         present to potential investors in reliance on Section 5(d) of the
Securities Act, whether or
         not they retain copies of the communications.
We partially depend on intellectual property licensed from third parties, page
59

5.       We note your disclosure regarding an option agreement with the
University of Alberta
         pursuant to which you in-license key patent applications for your Exon
51 skipping
         Antibody Oligonucleotide Conjugate for Duchenne muscular dystrophy and
future
         product candidates. Please provide a summary of the material terms of
this agreement in
         the Business section and file this agreement as an exhibit or tell us
why you do not believe
         it is required.
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Research Collaboration and License Agreement With Lilly, page 85

6.       Please disaggregate the milestones payments into those for
development, regulatory, and
         commercialization for further transparency into the collaboration and
license agreement
         with Lilly.
Critical Accounting Policies and Estimates
Stock Based Compensation
Common Stock Valuations, page 94

7.       Once you have an estimated offering price or range, please explain to
us how you
         determined the fair value of the common stock underlying your equity
issuances and the
         reasons for any differences between the recent valuations of your
common stock leading
         up to the IPO and the estimated offering price. This information will
help facilitate our
         review of your accounting for equity issuances including stock
compensation and
         beneficial conversion features.
 Sarah Boyce
FirstName LastNameSarah Boyce
Avidity Biosciences, Inc.
Comapany NameAvidity Biosciences, Inc.
April 30, 2020
Page 30,
April 3 2020 Page 3
FirstName LastName
Intellectual Property, page 124

8.       Please disclose which foreign jurisdiction or jurisdictions you are
referring to when you
         state that you have filed an "international" patent application.
Intellectual Property Relating to Our AOC Product Platform, page 126

9.       Please identify the foreign jurisdictions where you have filed patent
applications related to
         your product platform.
Principal Stockholders, page 176

10.      Please revise footnote (1) to clarify, if true, that Dr. Wong is the
sole person with voting
         and investment control over the shares held by RTW Investments and
footnote (2) to
         clarify, if true, that Bihua Chen is the sole person with such control
over the shares held
         by Cormorant Asset Management, or revise each to identify all natural
person or persons
         who have voting and investment control of the shares held by these
entities.
Notes to the Financial Statements
2. Summary of Significant Accounting Policies
Unaudited Pro Forma Information, page F-8

11.      Please tell us why it is appropriate to include the proceeds from the
sale of Series C
         convertible preferred stock in January 2020 and conversion into common
stock in the
         unaudited pro forma information here and throughout the filing as if
the transactions had
         occurred as of December 31, 2019.
       You may contact Christine Torney at 202-551-3652 or Mary Mast at
202-551-3613 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Ada D. Sarmento at 202-551-3798 or Mary Beth Breslin at 202-551-3625
with any other
questions.



                                                                Sincerely,

                                                                Division of
Corporation Finance
                                                                Office of Life
Sciences
cc:      Cheston J. Larson, Esq.