<SEC-DOCUMENT>0000860413-17-000035-index.html : 20170925
<SEC-HEADER>0000860413-17-000035.hdr.sgml : 20170925
<ACCEPTANCE-DATETIME>20170922173435
ACCESSION NUMBER:		0000860413-17-000035
CONFORMED SUBMISSION TYPE:	S-3
PUBLIC DOCUMENT COUNT:		5
FILED AS OF DATE:		20170925
DATE AS OF CHANGE:		20170922

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FIRST INTERSTATE BANCSYSTEM INC
		CENTRAL INDEX KEY:			0000860413
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				810331430
		STATE OF INCORPORATION:			MT
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		S-3
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-220594
		FILM NUMBER:		171098320

	BUSINESS ADDRESS:	
		STREET 1:		P O BOX 30918
		STREET 2:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116-0918
		BUSINESS PHONE:		4062555300

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FIRST INTERSTATE BANCSYSTEM OF MONTANA INC
		DATE OF NAME CHANGE:	19930615
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-3
<SEQUENCE>1
<FILENAME>a20170922-sx3.htm
<DESCRIPTION>S-3
<TEXT>
Document 1 - file: a20170922-sx3.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>fibk-exhibit51.htm
<DESCRIPTION>EXHIBIT 5.1
<TEXT>
Document 2 - file: fibk-exhibit51.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.2
<SEQUENCE>3
<FILENAME>fibk-exhibit232.htm
<DESCRIPTION>EXHIBIT 23.2
<TEXT>
Document 3 - file: fibk-exhibit232.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.3
<SEQUENCE>4
<FILENAME>fibk-exhibit233.htm
<DESCRIPTION>EXHIBIT 23.3
<TEXT>
Document 4 - file: fibk-exhibit233.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>5
<FILENAME>fibbancsyst2line4ca01.jpg
<TEXT>
Document 5 - file: fibbancsyst2line4ca01.jpg

</DOCUMENT>
</SEC-DOCUMENT>