Guggenheim Funds Distributors, LLC
                           2455 Corporate West Drive
                             Lisle, Illinois 60532


                                  July 6, 2017


Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549


                 Re: Guggenheim Defined Portfolios, Series 1625
                        File Nos. 333-218651 & 811-03763

Ladies/Gentlemen:

     The undersigned, Guggenheim Defined Portfolios, Series 1625 (the "Trust"),
by Guggenheim Funds Distributors, LLC, as the sponsor and depositor of the Trust
and of the units covered by the subject Registration Statement, pursuant to the
provisions of Rule 461 of the General Rules and Regulations of the Securities
and Exchange Commission (the "Commission") under the Securities Act of 1933,
hereby respectfully requests that the Commission consent to the filing of the
amendment to the Registration Statement and grant acceleration of the
effectiveness of said Registration Statement, as amended, so that the same may
become effective by 1 p.m. Eastern time on July 11, 2017, or as soon thereafter
as possible.

                                                               Very truly yours,

                                      Guggenheim Defined Portfolios, Series 1625

                                          By: Guggenheim Funds Distributors, LLC


                                                                 By: /s/ Amy Lee
                                                                 ---------------
                                                                         Amy Lee
                                                    Vice President and Secretary