    <SEC-DOCUMENT>0001193125-25-230071-index.html : 20251003
    <SEC-HEADER>0001193125-25-230071.hdr.sgml : 20251003
    <ACCEPTANCE-DATETIME>20251003160304
    ACCESSION NUMBER:		0001193125-25-230071
    CONFORMED SUBMISSION TYPE:	N-CSR
    PUBLIC DOCUMENT COUNT:		15
    CONFORMED PERIOD OF REPORT:	20250731
    FILED AS OF DATE:		20251003
    DATE AS OF CHANGE:		20251003
    EFFECTIVENESS DATE:		20251003

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			BLACKROCK MUNIASSETS FUND, INC.
    		CENTRAL INDEX KEY:			0000901243
    		ORGANIZATION NAME:
    		EIN:				223239638
    		STATE OF INCORPORATION:			MD
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		N-CSR
    		SEC ACT:		1940 Act
    		SEC FILE NUMBER:	811-07642
    		FILM NUMBER:		251373681

    	BUSINESS ADDRESS:
    		STREET 1:		100 BELLEVUE PARKWAY
    		CITY:			WILMINGTON
    		STATE:			DE
    		ZIP:			19809
    		BUSINESS PHONE:		800-441-7762

    	MAIL ADDRESS:
    		STREET 1:		100 BELLEVUE PARKWAY
    		CITY:			WILMINGTON
    		STATE:			DE
    		ZIP:			19809

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	MUNIASSETS FUND INC
    		DATE OF NAME CHANGE:	19930714

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	MUNIINCOME FUND INC
    		DATE OF NAME CHANGE:	19930517
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>N-CSR
    <SEQUENCE>1
    <FILENAME>d927228dncsr.htm
    <DESCRIPTION>BLACKROCK MUNIASSETS FUND, INC.
    <TEXT>
    Document 1 - file: d927228dncsr.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CERT
    <SEQUENCE>2
    <FILENAME>d927228dex99cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 302
    <TEXT>
    Document 2 - file: d927228dex99cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.906 CERT
    <SEQUENCE>3
    <FILENAME>d927228dex99906cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 906
    <TEXT>
    Document 3 - file: d927228dex99906cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.PROXYPOL
    <SEQUENCE>4
    <FILENAME>d927228dex99proxypol.htm
    <DESCRIPTION>PROXY VOTING POLICY AND PROCEDURES
    <TEXT>
    Document 4 - file: d927228dex99proxypol.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>g927228img1c934fd62.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: g927228img1c934fd62.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>g927228img3a0019f45.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: g927228img3a0019f45.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>g927228img7934ce0e3.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: g927228img7934ce0e3.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>g927228img992c38288.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: g927228img992c38288.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>g927228imga49a1fd11.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: g927228imga49a1fd11.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>g927228imgb26184dc7.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: g927228imgb26184dc7.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>g927228imge27a493c6.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: g927228imge27a493c6.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>g927228imge377b1b14.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: g927228imge377b1b14.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>g927228snap1.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g927228snap1.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>g927228sp16a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: g927228sp16a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>g927228sp16b.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: g927228sp16b.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>