    <SEC-DOCUMENT>0001193125-17-345863-index.html : 20171117
    <SEC-HEADER>0001193125-17-345863.hdr.sgml : 20171117
    <ACCEPTANCE-DATETIME>20171116213056
    ACCESSION NUMBER:		0001193125-17-345863
    CONFORMED SUBMISSION TYPE:	424B1
    PUBLIC DOCUMENT COUNT:		10
    FILED AS OF DATE:		20171117
    DATE AS OF CHANGE:		20171116

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			Arsanis, Inc.
    		CENTRAL INDEX KEY:			0001501697
    		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
    		IRS NUMBER:				273181608
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		424B1
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-221050
    		FILM NUMBER:		171209598

    	BUSINESS ADDRESS:
    		STREET 1:		890 WINTER STREET, SUITE 230
    		CITY:			WALTHAM
    		STATE:			MA
    		ZIP:			02451
    		BUSINESS PHONE:		781-819-5704

    	MAIL ADDRESS:
    		STREET 1:		890 WINTER STREET, SUITE 230
    		CITY:			WALTHAM
    		STATE:			MA
    		ZIP:			02451
    </SEC-HEADER>
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