Exhibit 21.1

Subsidiaries of First Interstate BancSystem, Inc.

	Subsidiary	State of Incorporation or Jurisdiction of Organization		Business Name
	First Interstate Bank	Montana		First Interstate Bank
	FI Statutory Trust I	Connecticut		FI Statutory Trust I
	FI Capital Trust II	Delaware		FI Capital Trust II
	FI Statutory Trust III	Delaware		FI Statutory Trust III
	FI Capital Trust IV	Delaware		FI Capital Trust IV
	FI Statutory Trust V	Delaware		FI Statutory Trust V
	FI Statutory Trust VI	Delaware		FI Statutory Trust VI
	Mountain South, LLC	Montana		Mountain South, LLC
	Northwest Bancorporation Capital Trust I	Washington		Northwest Bancorporation Capital Trust I