MEMORANDUM

                             FT 1720
                       File No. 333-150047

     The Prospectus and the Indenture filed with Amendment No.  3
of  the  Registration Statement on Form S-6 have been revised  to
reflect information regarding the execution of the Indenture  and
the  deposit  of  Securities on June 30, 2008 and  to  set  forth
certain statistical data based thereon.  In addition, there are a
number of other changes described below.

                         THE PROSPECTUS

Cover Page     The date of the Trusts has been added.

Pages 3-10     The following information for the Trusts appears:

               The   Aggregate  Value  of  Securities   initially
               deposited has been added.

               The initial number of units of the Trusts

               Sales charge

               The  Public  Offering Price per  Unit  as  of  the
               business day before the Initial Date of Deposit

               The Mandatory Termination Dates have been added.

Page 11        The   Report  of  Independent  Registered   Public
               Accounting Firm has been completed.

Pages 12-16    The Statements of Net Assets have been completed.

Pages 17-42    The Schedules of Investments have been completed.

Back Cover     The date of the Prospectus has been included.

 THE TRUST AGREEMENT AND STANDARD TERMS AND CONDITIONS OF TRUST

               The  Trust Agreement has been conformed to reflect
               the execution thereof.

                                    CHAPMAN AND CUTLER LLP

June 30, 2008