Chapman and Cutler LLP
                                 111 West Monroe
                             Chicago, Illinois 60603

                               September 21, 2011



Securities and Exchange Commission
100 F Street NE
Washington, D.C.  20549


                 Re: Guggenheim Defined Portfolios, Series 817
                      Guggenheim BulletShares(R) 2011-2017
                         Corporate Bond Ladder Portfolio
                                of ETFs, Series 2
                              File No. 333-175817
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Ladies and Gentlemen:

         On behalf of Guggenheim Funds Distributors, Inc., depositor, sponsor
and underwriter of the Guggenheim Defined Portfolios, Series 817, consisting of
the above-captioned trusts (the "Trusts"), there is enclosed Amendment No. 2 to
the Registration Statement on Form S-6 relating to securities of Guggenheim
Defined Portfolios, Series 817 (the "Fund").

         The Reference Trust Agreement was entered into by Guggenheim Funds
Distributors, Inc., as Depositor, and The Bank of New York Mellon, as Trustee,
on the date hereof, and Securities (or delivery statements relating to contracts
for the purchase thereof) in the aggregate amount of the portfolio(s) have been
deposited with the Trustee. In connection therewith the Trustee is prepared to
establish book entry positions which are being retained by the Trustee for
delivery after the effectiveness of the Registration Statement.

         In addition to Amendment No. 2, the exhibits listed therein are
submitted herewith.

         Except as indicated in the Memorandum of Changes, the changes in the
Prospectus represent primarily the completion of various statements regarding
the Securities deposited in the Trusts and the dates of record, deposit,
distribution, termination and evaluation, together with a list of the Securities
which will comprise the portfolio of the Trusts, the Statement of Financial
Condition of the Trusts and the Report of Independent Registered Public
Accounting Firm.

         We have appreciated the courtesy and cooperation of the members of the
Staff and if there are any questions on which we may be of assistance, please do
not hesitate to call either Eric F. Fess (312-845-3781) or Morrison C. Warren
(312-845-3484) collect.

                                                               Very truly yours,

                                                      /s/ Chapman and Cutler LLP
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                                                          CHAPMAN AND CUTLER LLP