Exhibit 5(b)


                         LeBoeuf, Lamb, Greene & MacRae
                                     L.L.P.
       A limited liability partnership including professional corporations

                              125 West 55th Street
                             New York, NY 10019-5389
                                                               January 20, 2004



MDU Resources Group, Inc.
Schuchart Building
918 East Divide Avenue, P.O. Box 5650
Bismarck, North Dakota  58506-5650

Ladies and Gentlemen:

          We are acting as counsel for MDU Resources Group, Inc., a Delaware
corporation (the "Company"), in connection with the preparation and filing with
the Securities and Exchange Commission (the "Commission") under the Securities
Act of 1933, as amended (the "Securities Act"), of the Company's registration
statement on Form S-8 (the "Registration Statement") for the registration of
1,500,000 shares of the Company's common stock, par value $1.00 per share (the
"Stock"), and the preference share purchase rights attached thereto (the
"Rights"), to be issued and sold pursuant to the Company's 1998 Option Award
Program (the "Plan").

          In connection with this opinion, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of (i) the Registration
Statement, (ii) the Rights Agreement, dated as of November 12, 1998, between the
Company and Wells Fargo Bank, N.A. (formerly known as Norwest Bank Minnesota,
N.A.), as Rights Agent, together with the exhibits thereto (the "Rights
Agreement"), pursuant to which the Rights were created, (iii) the Restated
Certificate of Incorporation and the Bylaws, as amended, of the Company, as in
effect on the date hereof, (iv) resolutions of the Board of Directors of the
Company, dated February 15, 2001, authorizing the issuance of the Stock and (v)
such other instruments, certificates, records and documents, and such matters of
law, as we have considered necessary or appropriate for the purposes hereof. In
such examination, we have assumed the genuineness of all signatures, the
authenticity of all documents submitted to us as originals, the conformity to
the original documents of all documents submitted to us as copies and the
authenticity of the originals of such latter documents. As to any facts material
to our opinion, we have, when relevant facts were not independently established,
relied upon the aforesaid Registration Statement, Rights Agreement, resolutions,
instruments, certificates, records and documents. We have also assumed the
regularity of all corporate procedures.





          Based upon the foregoing, and subject to the limitations and
qualifications contained in this opinion, we are of the opinion that:

          1.   The issuance of the Stock has been duly authorized by the Board
               of Directors of the Company.

          2.   When the Federal Energy Regulatory Commission, the Montana Public
               Service Commission and the Public Service Commission of Wyoming
               shall have issued orders authorizing the issuance and sale of the
               Stock, and provided that such orders remain in full force and
               effect and have not been amended, rescinded or repealed, the
               Stock will be validly issued, fully paid and non-assessable when
               the Stock shall have been issued, sold and delivered for the
               consideration contemplated in the Plan.

          3.   The issuance of the Rights has been validly authorized by all
               necessary corporate action on the part of the Company and, when
               issued in accordance with the Rights Agreement, the Rights will
               be legally issued and binding obligations of the Company.

          We express no opinion with respect to any laws other than the General
Corporation Law of the State of Delaware, the applicable provisions of the
Delaware Constitution and the reported judicial decisions interpreting the
Delaware laws, and the federal laws of the United States.

          We hereby consent to the use of this opinion as an exhibit to the
Registration Statement. In giving such consent, we do not thereby concede that
we are within the category of persons whose consent is required under Section 7
of the Securities Act or the rules and regulations of the Commission thereunder.

                                      Very truly yours,

                                      /s/ LeBoeuf, Lamb, Greene & MacRae, L.L.P.