Rule 424(b)(3)
                                                              File No. 333-06127


                            MDU Resources Group, Inc.
                         Automatic Dividend Reinvestment
                             and Stock Purchase Plan
                  Supplement to Prospectus Dated August 1, 1996


     MDU Resources  Group,  Inc.  (Company) is expanding its Automatic  Dividend
Reinvestment and Stock Purchase Plan (Plan) so that interested investors who are
legal residents in any of the 50 states may  participate in the Plan.  Effective
August 15, 1998,  participation  in the Plan is open to (i) any  stockholder  of
record of any class of the Company's  capital stock,  (ii) beneficial  owners of
the Company's capital stock, as described in the Prospectus and (iii) any person
who is a  legal  resident  in  any  of the 50  states  who  wants  to  become  a
stockholder  by making an initial cash payment at the time of  enrollment of not
less than $50 but not more than $5,000.

     To the extent required by applicable law in certain  jurisdictions,  shares
of common stock offered under the Plan to persons not presently  stockholders of
the Company are offered only through Norwest Investment Services, Inc.

July 13, 1998