BEAR, STEARNS & CO. INC.
245 Park Avenue
New York, New York 10167
(212) 272-2500
November 16, 1994
VIA EDGAR
Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549
Re: Insured Municipal Securities Trust, Series 21
File No. 33-28702
Gentlemen:
As Sponsors of the above-referenced Trust, we are writing this
letter to certify that:
(1) the form of Prospectus that would have been filed under Rule
497(b) of the Securities Act of 1933, does not differ from that contained
in the most recent Post-Effective Amendment to the Registration Statement
on Form S-6 (the "Registration Statement"), and
(2) the text of the most recent Registration Statement was filed
electronically with the Securities and Exchange Commission on October 26,
1994 and became effective October 28, 1994 pursuant to Rule 485(b).
Insured Municipal Securities Trust,
Series 21
BEAR, STEARNS & CO. INC.
GRUNTAL & CO. INCORPORATED
By:
Peter J. DeMarco
as agent for the Sponsors
