September 8, 2025

Bruce Steel
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa
Suite 105
La Jolla, CA 92037

       Re: Equillium, Inc.
           Form 10-K for the Year Ended December 31, 2024
           File No. 001-38692
Dear Bruce Steel:

       We have limited our review of your filing to the financial statements
and related
disclosures and have the following comment.

       Please respond to this letter within ten business days by providing the
requested
information or advise us as soon as possible when you will respond. If you do
not believe
this comment applies to your facts and circumstances, please tell us why in
your response.

       After reviewing your response to this letter, we may have additional
comments.

Management's Discussion and Analysis of Financial Condition and Results of
Operations
Results of Operations, page 93

1.     To the extent you track any of your costs by product candidate and
indication, please
       provide disclosures to be presented in future filings to separately
disclose your
       research and development expenses by product candidate and indication.
To the extent
       you are not able to quantify any such costs by product candidate or
indication,
       disclose that fact as well as the reasons why not, and provide separate
quantification
       for unallocated expenses by their natural expense categories or type.
The total of
       quantifiable expenses should reconcile to the amount of research and
development
       expenses presented on the face of your Statement of Operations. We note
from your
       disclosures in the Notes to Consolidated Financial Statement that you
are able to
       separately classify accrued expenses for Biocon clinical development
related to
       ulcerative colitis study. We also note from disclosures in the
Comparison of the Years
       Ended December 31, 2024 and 2023 in Results of Operations that you are
able to
       distinguish preclinical and clinical research and development expenses.
 September 8, 2025
Page 2

        In closing, 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.

       Please contact Christine Torney at 202-551-3652 or Kevin Vaughn at
202-551-3494
with any questions.



                                                          Sincerely,

                                                          Division of
Corporation Finance
                                                          Office of Life
Sciences