    <SEC-DOCUMENT>0000950123-17-008682-index.html : 20171006
    <SEC-HEADER>0000950123-17-008682.hdr.sgml : 20171006
    <ACCEPTANCE-DATETIME>20170929101106
    <PRIVATE-TO-PUBLIC>
    ACCESSION NUMBER:		0000950123-17-008682
    CONFORMED SUBMISSION TYPE:	DRS/A
    PUBLIC DOCUMENT COUNT:		15
    FILED AS OF DATE:		20170929
    <PUBLIC-REL-DATE>20171006
    DATE AS OF CHANGE:		20170929

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			Spero Therapeutics, Inc.
    		CENTRAL INDEX KEY:			0001701108
    		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
    		IRS NUMBER:				000000000
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		DRS/A
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	377-01690
    		FILM NUMBER:		171109435

    	BUSINESS ADDRESS:
    		STREET 1:		675 MASSACHUSETTS AVENUE
    		STREET 2:		14TH FLOOR
    		CITY:			CAMBRIDGE
    		STATE:			MA
    		ZIP:			02139
    		BUSINESS PHONE:		857-242-1600

    	MAIL ADDRESS:
    		STREET 1:		675 MASSACHUSETTS AVENUE
    		STREET 2:		14TH FLOOR
    		CITY:			CAMBRIDGE
    		STATE:			MA
    		ZIP:			02139

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	Spero Therapeutics, LLC
    		DATE OF NAME CHANGE:	20170316
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>DRS/A
    <SEQUENCE>1
    <FILENAME>filename1.htm
    <TEXT>
    Document 1 - file: filename1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10
    <SEQUENCE>2
    <FILENAME>filename2.htm
    <TEXT>
    Document 2 - file: filename2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10
    <SEQUENCE>3
    <FILENAME>filename3.htm
    <TEXT>
    Document 3 - file: filename3.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>g431217g14o23.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 4 - file: g431217g14o23.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>g431217g19n51.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: g431217g19n51.jpg

    </DOCUMENT>
    <DOCUMENT>
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    <SEQUENCE>6
    <FILENAME>g431217g32y96.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: g431217g32y96.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>g431217g41w64.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: g431217g41w64.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>g431217g42o58.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: g431217g42o58.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>g431217g58u08.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: g431217g58u08.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>g431217g74a40.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: g431217g74a40.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>g431217g74g36.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: g431217g74g36.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>g431217g74p02.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: g431217g74p02.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>g431217g78m75.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: g431217g78m75.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>g431217g81r65.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 14 - file: g431217g81r65.jpg

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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>g431217g96e78.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: g431217g96e78.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>