    <SEC-DOCUMENT>0001193125-23-251245-index.html : 20231005
    <SEC-HEADER>0001193125-23-251245.hdr.sgml : 20231005
    <ACCEPTANCE-DATETIME>20231005103230
    ACCESSION NUMBER:		0001193125-23-251245
    CONFORMED SUBMISSION TYPE:	N-CSR
    PUBLIC DOCUMENT COUNT:		24
    CONFORMED PERIOD OF REPORT:	20230731
    FILED AS OF DATE:		20231005
    DATE AS OF CHANGE:		20231005
    EFFECTIVENESS DATE:		20231005

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			BLACKROCK MUNIYIELD QUALITY FUND III, INC.
    		CENTRAL INDEX KEY:			0000883412
    		IRS NUMBER:				223165131
    		FISCAL YEAR END:			1031

    	FILING VALUES:
    		FORM TYPE:		N-CSR
    		SEC ACT:		1940 Act
    		SEC FILE NUMBER:	811-06540
    		FILM NUMBER:		231310097

    	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:	BLACKROCK MUNIYIELD QUALITY FUND III, INC
    		DATE OF NAME CHANGE:	20101109

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	BLACKROCK MUNIYIELD INSURED FUND, INC
    		DATE OF NAME CHANGE:	20070612

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	MUNIYIELD INSURED FUND INC
    		DATE OF NAME CHANGE:	19920717
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>N-CSR
    <SEQUENCE>1
    <FILENAME>d531006dncsr.htm
    <DESCRIPTION>BLACKROCK MUNIYIELD QUALITY FUND III, INC.
    <TEXT>
    Document 1 - file: d531006dncsr.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.CERT
    <SEQUENCE>2
    <FILENAME>d531006dex99cert.htm
    <DESCRIPTION>CERTIFICATION PURSUANT TO SECTION 302
    <TEXT>
    Document 2 - file: d531006dex99cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.906CERT
    <SEQUENCE>3
    <FILENAME>d531006dex99906cert.htm
    <DESCRIPTION>CERTIFICATION PURSUANT TO SECTION 906
    <TEXT>
    Document 3 - file: d531006dex99906cert.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.PROXYPOL
    <SEQUENCE>4
    <FILENAME>d531006dex99proxypol.htm
    <DESCRIPTION>PROXY VOTING POLICY AND PROCEDURES
    <TEXT>
    Document 4 - file: d531006dex99proxypol.htm

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    <DOCUMENT>
    <TYPE>EX-99.GLOBALCORPGOV
    <SEQUENCE>5
    <FILENAME>d531006dex99globalcorpgov.htm
    <DESCRIPTION>GLOBAL CORPORATE GOVERNANCE & ENGAGEMENT PRINCIPLES
    <TEXT>
    Document 5 - file: d531006dex99globalcorpgov.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.USCORPGOV
    <SEQUENCE>6
    <FILENAME>d531006dex99uscorpgov.htm
    <DESCRIPTION>CORPORATE GOVERNANCE AND PROXY VOTING GUIDELINES FOR U.S. SECURITIES
    <TEXT>
    Document 6 - file: d531006dex99uscorpgov.htm

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    <DESCRIPTION>GRAPHIC
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    Document 7 - file: g482724bblk.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 8 - file: g482724black1.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 9 - file: g482724black2.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 10 - file: g482724black24.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 11 - file: g482724g42l24.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 12 - file: g482724g50p51.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 13 - file: g528083dsp1.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 14 - file: g528083dsp112.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 15 - file: g528083dsp1a.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 16 - file: g528083gdsp012.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 17 - file: g528083gdsp04.jpg

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    <SEQUENCE>18
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: g528083gdsp06.jpg

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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: g528083gdsp09.jpg

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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 20 - file: g528083gdsp15.jpg

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    <SEQUENCE>21
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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 21 - file: g528083gdsp18.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 22 - file: g528083gdsp21.jpg

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    <DESCRIPTION>GRAPHIC
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    Document 23 - file: g528083photo_01mips.jpg

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    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 24 - file: g528083sig_01mips.jpg

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