N-CSR Item 12(b) - Exhibits: Certifications

                           SECTION 906 CERTIFICATION

Pursuant to 18 U.S.C.{section} 1350, the undersigned officers of FEDERATED
MUNICIPAL SECURITIES INCOME TRUST ON BEHALF OF: FEDERATED CALIFORNIA MUNICIPAL
INCOME FUND, FEDERATED MICHIGAN INTERMEDIATE MUNICIPAL TRUST, FEDERATED
MUNICIPAL HIGH YIELD ADVANTAGE FUND, FEDERATED NEW YORK MUNICIPAL INCOME FUND,
FEDERATED NORTH CAROLINA MUNICIPAL INCOME FUND, FEDERATED OHIO MUNICIPAL INCOME
FUND, FEDERATED PENNSYLVANIA MUNICIPAL INCOME FUND (the "Registrant"), hereby
certify, to the best of our knowledge, that the Registrant's Report on Form N-
CSR for the period ended August 31, 2007 (the "Report") fully complies with the
requirements of Section 13(a) or 15(d), as applicable, of the Securities and
Exchange Act of 1934 and that the information contained in the Report fairly
presents, in all material respects, the financial condition and results of
operations of the Registrant.


Dated: October 23, 2007

/s/ J. Christopher Donahue
Name:  J. Christopher Donahue
Title: President, Principal Executive Officer



Dated: October 23, 2007

/s/ Richard A. Novak
Name:  Richard A. Novak
Title: Treasurer, Principal Financial Officer

This certification is being furnished solely pursuant to 18 U.S.C.{section} 1350
and is not being filed as part of the Report or as a separate disclosure
document.