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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 CtfTy0W0Mr3DlKKdUpkRlygmiMf8W3lKuOJPTUFqCCtPYhrMpiqfRhftO/2/UAoU
 IWueQeIwJG7K1H2DVfSpUA==

<SEC-DOCUMENT>9999999995-07-001557.txt : 20070501
<SEC-HEADER>9999999995-07-001557.hdr.sgml : 20070501
<ACCEPTANCE-DATETIME>20070501001544
ACCESSION NUMBER:		9999999995-07-001557
CONFORMED SUBMISSION TYPE:	EFFECT
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20070430
DATE AS OF CHANGE:		20070501
EFFECTIVENESS DATE:		20070430

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MFS MUNICIPAL SERIES TRUST
		CENTRAL INDEX KEY:			0000751656
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			0331

	FILING VALUES:
		FORM TYPE:		EFFECT
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-139458
		FILM NUMBER:		07803104

	BUSINESS ADDRESS:	
		STREET 1:		500 BOYLSTON ST
		STREET 2:		15TH FL
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		18006372929

	MAIL ADDRESS:	
		STREET 1:		500 BOYLSTON STREET
		STREET 2:		15TH FL
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MFS MANAGED MULTI STATE MUNICIPAL BOND TRUST
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MFS MANAGED MULTI STATE TAX EXEMPT TRUST
		DATE OF NAME CHANGE:	19890410
<SERIES-AND-CLASSES-CONTRACTS-DATA>
<MERGER-SERIES-AND-CLASSES-CONTRACTS>
<MERGER>
<ACQUIRING-DATA>
CENTRAL INDEX KEY:			0000751656
<SERIES>
<SERIES-ID>S000002536
<SERIES-NAME>MFS Municipal Income Fund
<CLASS-CONTRACT>
<CLASS-CONTRACT-ID>C000042676
<CLASS-CONTRACT-NAME>Class A1 Shares
</CLASS-CONTRACT>
</SERIES>
</ACQUIRING-DATA>
<TARGET-DATA>
CENTRAL INDEX KEY:			0000063068
<SERIES>
<SERIES-ID>S000002436
<SERIES-NAME>MFS Municipal Bond Fund
<CLASS-CONTRACT>
<CLASS-CONTRACT-ID>C000006518
<CLASS-CONTRACT-NAME>A
<CLASS-CONTRACT-TICKER-SYMBOL>MMBFX
</CLASS-CONTRACT>
</SERIES>
</TARGET-DATA>
</MERGER>
<MERGER>
<ACQUIRING-DATA>
CENTRAL INDEX KEY:			0000751656
<SERIES>
<SERIES-ID>S000002536
<SERIES-NAME>MFS Municipal Income Fund
<CLASS-CONTRACT>
<CLASS-CONTRACT-ID>C000042677
<CLASS-CONTRACT-NAME>Class B1 Shares
</CLASS-CONTRACT>
</SERIES>
</ACQUIRING-DATA>
<TARGET-DATA>
CENTRAL INDEX KEY:			0000063068
<SERIES>
<SERIES-ID>S000002436
<SERIES-NAME>MFS Municipal Bond Fund
<CLASS-CONTRACT>
<CLASS-CONTRACT-ID>C000006519
<CLASS-CONTRACT-NAME>B
<CLASS-CONTRACT-TICKER-SYMBOL>MMBBX
</CLASS-CONTRACT>
</SERIES>
</TARGET-DATA>
</MERGER>
</MERGER-SERIES-AND-CLASSES-CONTRACTS>
</SERIES-AND-CLASSES-CONTRACTS-DATA>
</SEC-HEADER>
<DOCUMENT>
<TYPE>EFFECT
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0101</schemaVersion>

    <submissionType>EFFECT</submissionType>

    <act>33</act>

    <testOrLive>LIVE</testOrLive>

    <effectiveData>
        <finalEffectivenessDispDate>2007-04-30</finalEffectivenessDispDate>
        <finalEffectivenessDispTime>11:30:00</finalEffectivenessDispTime>
        <form>N-14</form>
        <filer>
            <cik>0000751656</cik>
            <entityName>MFS MUNICIPAL SERIES TRUST</entityName>
            <fileNumber>333-139458</fileNumber>
            <seriesClassContractData>
                <merger>
                    <acquiringCik>0000751656</acquiringCik>
                    <acquiringEntityName>MFS MUNICIPAL SERIES TRUST</acquiringEntityName>
                    <acquiringSeriesId>S000002536</acquiringSeriesId>
                    <acquiringSeriesName>MFS Municipal Income Fund</acquiringSeriesName>
                    <acquiringClassContractId>C000042676</acquiringClassContractId>
                    <acquiringClassContractName>Class A1 Shares</acquiringClassContractName>
                    <targetCik>0000063068</targetCik>
                    <targetEntityName>MFS SERIES TRUST IV</targetEntityName>
                    <targetSeriesId>S000002436</targetSeriesId>
                    <targetSeriesName>MFS Municipal Bond Fund</targetSeriesName>
                    <targetClassContractId>C000006518</targetClassContractId>
                    <targetClassContractName>A</targetClassContractName>
                </merger>
                <merger>
                    <acquiringCik>0000751656</acquiringCik>
                    <acquiringEntityName>MFS MUNICIPAL SERIES TRUST</acquiringEntityName>
                    <acquiringSeriesId>S000002536</acquiringSeriesId>
                    <acquiringSeriesName>MFS Municipal Income Fund</acquiringSeriesName>
                    <acquiringClassContractId>C000042677</acquiringClassContractId>
                    <acquiringClassContractName>Class B1 Shares</acquiringClassContractName>
                    <targetCik>0000063068</targetCik>
                    <targetEntityName>MFS SERIES TRUST IV</targetEntityName>
                    <targetSeriesId>S000002436</targetSeriesId>
                    <targetSeriesName>MFS Municipal Bond Fund</targetSeriesName>
                    <targetClassContractId>C000006519</targetClassContractId>
                    <targetClassContractName>B</targetClassContractName>
                </merger>
            </seriesClassContractData>
        </filer>
    </effectiveData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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