CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,
               AS ADOPTED PURSUANT TO SECTION 906
                OF THE SARBANES-OXLEY ACT OF 2002


     Each of the undersigned, Martin A. White, the Chairman of
the Board, President and Chief Executive Officer, and Warren L.
Robinson, the Executive Vice President and Chief Financial
Officer of MDU Resources Group, Inc. (the "Company"), DOES HEREBY
CERTIFY that:

     1.  The Company's Quarterly Report on Form 10-Q for the
quarter ended March 31, 2004 (the "Report"), fully complies with
the requirements of Section 13(a) of the Securities Exchange Act
of 1934; and

     2.  Information contained in the Report fairly presents, in
all material respects, the financial condition and results of
operation of the Company.

     IN WITNESS WHEREOF, each of the undersigned has executed
this statement this 7th day of May, 2004.


                               /s/ Martin A. White
                              Martin A. White
                              Chairman of the Board, President and
                              Chief Executive Officer



                               /s/ Warren L. Robinson
                              Warren L. Robinson
                              Executive Vice President and
                              Chief Financial Officer


A signed original of this written statement required by Section
906 has been provided to MDU Resources Group, Inc. and will be
retained by MDU Resources Group, Inc. and furnished to the
Securities and Exchange Commission or its staff upon request.