UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported) May 19, 2005 (May 5, 2005) MDU Resources Group, Inc. (Exact name of registrant as specified in its charter) Delaware 1-3480 41-0423660 (State or other jurisdiction (Commission (I.R.S. Employer of incorporation) File Number) Identification No.) Schuchart Building 918 East Divide Avenue P.O. Box 5650 Bismarck, North Dakota 58506-5650 (Address of principal executive offices) (Zip Code) Registrant's telephone number, including area code (701) 222-7900 Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: - Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) - Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) - Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) - Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Item 8.01. Other Events. In April 2005, Fidelity Exploration & Production Company, an indirect wholly owned subsidiary of MDU Resources Group, Inc. (MDU), announced that it had entered into Purchase and Sale Agreements relating to the acquisition of certain natural gas and oil producing properties in south Texas. The acquisition was completed on May 5, 2005. For additional information regarding this acquisition, reference is made to the Current Reports on Form 8-K of MDU filed with the Securities and Exchange Commission on April 25, 2005 and April 29, 2005. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. MDU RESOURCES GROUP, INC. Date May 19, 2005 BY /s/ Paul K. Sandness Paul K. Sandness General Counsel and Secretary