United States securities and exchange commission logo

                          May 15, 2023

       Andrew Obenshain
       President and Chief Executive Officer
       bluebird bio, Inc.
       455 Grand Union Boulevard
       Somerville, MA 02145

                                                        Re: bluebird bio, Inc.
Statement on Form S-3
                                                            Filed May 9, 2023
                                                            File No. 333-271772

       Dear Andrew Obenshain:

              This is to advise you that we have not reviewed and will not
review your registration

               Please refer to Rules 460 and 461 regarding requests for
acceleration. 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 Alan
Campbell at 202-551-4224 with any questions.


                          Division of Corporation Finance

                          Office of Life Sciences
       cc:                                              Wesley C. Holmes, Esq.