    <SEC-DOCUMENT>0001133228-24-011740-index.html : 20241231
    <SEC-HEADER>0001133228-24-011740.hdr.sgml : 20241231
    <ACCEPTANCE-DATETIME>20241231092941
    ACCESSION NUMBER:		0001133228-24-011740
    CONFORMED SUBMISSION TYPE:	N-CSR
    PUBLIC DOCUMENT COUNT:		11
    CONFORMED PERIOD OF REPORT:	20241031
    FILED AS OF DATE:		20241231
    DATE AS OF CHANGE:		20241231
    EFFECTIVENESS DATE:		20241231

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			WESTERN ASSET MUNICIPAL HIGH INCOME FUND INC.
    		CENTRAL INDEX KEY:			0000830487
    		ORGANIZATION NAME:
    		IRS NUMBER:				000000000
    		STATE OF INCORPORATION:			MD
    		FISCAL YEAR END:			1031

    	FILING VALUES:
    		FORM TYPE:		N-CSR
    		SEC ACT:		1940 Act
    		SEC FILE NUMBER:	811-05497
    		FILM NUMBER:		241591361

    	BUSINESS ADDRESS:
    		STREET 1:		620 EIGHTH AVENUE
    		STREET 2:		47TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10018
    		BUSINESS PHONE:		888-777-0102

    	MAIL ADDRESS:
    		STREET 1:		620 EIGHTH AVENUE
    		STREET 2:		47TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10018

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	MUNICIPAL HIGH INCOME FUND INC
    		DATE OF NAME CHANGE:	19920703

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	SPECIAL OPPORTUNITIES MUNICIPAL FUND INC
    		DATE OF NAME CHANGE:	19881025
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>N-CSR
    <SEQUENCE>1
    <FILENAME>wahiof-efp12395_ncsr.htm
    <DESCRIPTION>WESTERN ASSET MUNICIPAL HIGH INCOME FUND INC - N-CSR
    <TEXT>
    Document 1 - file: wahiof-efp12395_ncsr.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CODEETH
    <SEQUENCE>2
    <FILENAME>wamhif-efp12395_ex99code.htm
    <DESCRIPTION>CODE OF ETHICS
    <TEXT>
    Document 2 - file: wamhif-efp12395_ex99code.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CERT
    <SEQUENCE>3
    <FILENAME>wamhif-efp12395_ex99cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 3 - file: wamhif-efp12395_ex99cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.906CERT
    <SEQUENCE>4
    <FILENAME>wamhif-efp12395_ex99906cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 4 - file: wamhif-efp12395_ex99906cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>img6cbeaea27.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: img6cbeaea27.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>img7cd51d191.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: img7cd51d191.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>img8cca79982.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: img8cca79982.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>img85cdd7c25.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: img85cdd7c25.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>img93e739236.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: img93e739236.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>img8766b2d84.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: img8766b2d84.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>imgc4bc52023.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: imgc4bc52023.gif

    </DOCUMENT>
    </SEC-DOCUMENT>