    <SEC-DOCUMENT>0001193125-21-208678-index.html : 20210706
    <SEC-HEADER>0001193125-21-208678.hdr.sgml : 20210706
    <ACCEPTANCE-DATETIME>20210706154617
    ACCESSION NUMBER:		0001193125-21-208678
    CONFORMED SUBMISSION TYPE:	N-CSR
    PUBLIC DOCUMENT COUNT:		20
    CONFORMED PERIOD OF REPORT:	20210430
    FILED AS OF DATE:		20210706
    DATE AS OF CHANGE:		20210706
    EFFECTIVENESS DATE:		20210706

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			BLACKROCK MUNIASSETS FUND, INC.
    		CENTRAL INDEX KEY:			0000901243
    		IRS NUMBER:				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:		211073938

    	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>d509759dncsr.htm
    <DESCRIPTION>BLACKROCK MUNIASSETS FUND, INC
    <TEXT>
    Document 1 - file: d509759dncsr.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CERT
    <SEQUENCE>2
    <FILENAME>d509759dex99cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 302
    <TEXT>
    Document 2 - file: d509759dex99cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.906 CERT
    <SEQUENCE>3
    <FILENAME>d509759dex99906cert.htm
    <DESCRIPTION>CERTIFICATIONS PURSUANT TO SECTION 906
    <TEXT>
    Document 3 - file: d509759dex99906cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.PROXYPOL
    <SEQUENCE>4
    <FILENAME>d509759dex99proxypol.htm
    <DESCRIPTION>PROXY VOTING POLICY AND PROCEDURES
    <TEXT>
    Document 4 - file: d509759dex99proxypol.htm

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    <DOCUMENT>
    <TYPE>EX-99.GLOBAL.CORP.GO
    <SEQUENCE>5
    <FILENAME>d509759dex99globalcorpgo.htm
    <DESCRIPTION>GLOBAL CORPORATE GOVERNANCE & ENGAGEMENT PRINCIPLES
    <TEXT>
    Document 5 - file: d509759dex99globalcorpgo.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.US.CORP.GOV
    <SEQUENCE>6
    <FILENAME>d509759dex99uscorpgov.htm
    <DESCRIPTION>CORPORATE GOVERNANCE AND PROXY VOTING GUIDELINES FOR U.S. SECURITIES
    <TEXT>
    Document 6 - file: d509759dex99uscorpgov.htm

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    <SEQUENCE>7
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: g508548g00d02.jpg

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    <SEQUENCE>8
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: g508548g00d03.jpg

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    <SEQUENCE>9
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: g508548g00d05.jpg

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    <SEQUENCE>10
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: g508548g00d06.jpg

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    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>g508548g42l24.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: g508548g42l24.jpg

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    <SEQUENCE>12
    <FILENAME>g509759g21y91.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: g509759g21y91.jpg

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    <SEQUENCE>13
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g509759g31y41.jpg

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    <SEQUENCE>14
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: g509759g36e00.jpg

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    <SEQUENCE>15
    <FILENAME>g509759g42l24.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: g509759g42l24.jpg

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    <DOCUMENT>
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    <SEQUENCE>16
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: g509759g55f16.jpg

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    <SEQUENCE>17
    <FILENAME>g509759g68j89.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 17 - file: g509759g68j89.jpg

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    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>g509759leaf.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: g509759leaf.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>g509759photo_01mips.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: g509759photo_01mips.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>g509759sig_01mips.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 20 - file: g509759sig_01mips.jpg

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