Chapman and Cutler LLP 111 West Monroe Street Chicago, Illinois 60603 February 21, 2018 Mr. Edward Bartz Division of Investment Management Securities and Exchange Commission 100 F Street, N.E. Washington, DC 20549 Re: Guggenheim Defined Portfolios, Series 1725 Total Income Portfolio, Series 12 File Nos. 333-222230 and 811-03763 ------------------------------------------------------------------------------- Dear Mr. Bartz: This letter is in response to your comment given during a telephone conversation with our office regarding the registration statement on Form S-6 for Guggenheim Defined Portfolios, Series 1725, filed on December 21, 2017, with the Securities and Exchange Commission (the "Commission"). The registration statement proposes to offer the Total Income Portfolio, Series 12 (the "Trust"). PROSPECTUS Investment Summary -- Principal Risks 1. The duration example in the seventh bullet uses a duration of five years. Please confirm that the average weighted duration of the fixed-income securities held indirectly by the Trust is approximately five years or less. If not, please revise this example to reflect the average weighted duration of the fixed-income securities. Response: The sponsor confirms that the average weighted duration of the fixed-income securities held indirectly by the Trust is approximately five years or less and, therefore, the example does not need to be revised. We appreciate your prompt attention to this registration statement. If you have any questions or comments or would like to discuss our responses to your questions, please feel free to contact the undersigned at (312) 845-3484. Very truly yours, CHAPMAN AND CUTLER LLP By /s/ Morrison C. Warren ------------------------- Morrison C. Warren