EXHIBIT 23.4
 
                       [LETTERHEAD OF ERNST & YOUNG LLP]
 
                        CONSENT OF INDEPENDENT AUDITORS
 
    We consent to the reference to our firm under the caption "Experts" in the
Registration Statement (Form S-4) and related Prospectus of First Bank System,
Inc. (the Company) for the registration of 115,000,000 shares of its common
stock and 6,000,000 shares of its 8 1/8% cumulative preferred stock and to the
incorporation by reference therein of our report dated January 9, 1997, with
respect to the consolidated financial statements of the Company included in its
Annual Report (Form 10-K) for the year ended December 31, 1997, filed with the
Securities and Exchange Commission.
 
ERNST & YOUNG LLP
Minneapolis, Minnesota
June 16, 1997