SEARS MUNICIPAL TRUST INSURED LONG TERM SERIES 40, 497, 1994-04-06

SEARS MUNICIPAL TRUST INSURED LONG TERM SERIES 40
497, 1994-04-06

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                                                  Rule 497(d)

                DEAN WITTER SELECT MUNICIPAL TRUST
                     SUPPLEMENT TO PROSPECTUS
                           APRIL 4, 1994


            The record date for each series of the Dean Witter
  Select Municipal Trust has been changed to the 9th day of each
  month.  The distribution date remains unchanged.


            The prospectus included in the Registration Statement for
  Dean Witter Select Municipal Trust, Insured Long Term Series 40 is hereby
  incorporated by reference.