    <SEC-DOCUMENT>0000860413-19-000029-index.html : 20190301
    <SEC-HEADER>0000860413-19-000029.hdr.sgml : 20190301
    <ACCEPTANCE-DATETIME>20190301142147
    ACCESSION NUMBER:		0000860413-19-000029
    CONFORMED SUBMISSION TYPE:	PRE 14A
    PUBLIC DOCUMENT COUNT:		7
    CONFORMED PERIOD OF REPORT:	20190502
    FILED AS OF DATE:		20190301
    DATE AS OF CHANGE:		20190301

    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:		PRE 14A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-34653
    		FILM NUMBER:		19648387

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

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

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	FIRST INTERSTATE BANCSYSTEM OF MONTANA INC
    		DATE OF NAME CHANGE:	19930615
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>PRE 14A
    <SEQUENCE>1
    <FILENAME>a2018proxy.htm
    <DESCRIPTION>PRE 14A
    <TEXT>
    Document 1 - file: a2018proxy.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>avgneocompmixa02.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 3 - file: avgneocompmixa02.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>ceoneopaymix19.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 4 - file: ceoneopaymix19.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>fibbancsyst2line4ca17.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: fibbancsyst2line4ca17.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>financialgraphsa05.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: financialgraphsa05.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>preliminaryproxycard001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: preliminaryproxycard001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>text10.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: text10.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>