Exhibit 21.1

Subsidiaries of First Interstate BancSystem, Inc.

	State of Incorporation or
Subsidiary	Jurisdiction of Organization	Business Name
First Interstate Bank	Montana	First Interstate Bank
Commerce Financial, Inc.	Montana	Commerce Financial, Inc.
First Interstate Statutory Trust	Delaware	First Interstate Statutory Trust
i_Tech Corporation	Montana	i_Tech Corporation
FIB, LLC	Montana	FIB, LLC
FI Reinsurance, Ltd.	Nevis Island, West Indies	FI Reinsurance, Ltd.
First Interstate Insurance Agency, Inc.	Montana	First Interstate Insurance Agency, Inc.
FIBCT, LLC	Montana	Crytech