July 7 , 2006

MDU Resources Announces Webcast of Second Quarter 2006 Earnings Conference Call
Bismarck, ND

MDU Resources Group, Inc. (NYSE:MDU) will webcast its second quarter 2006 earnings release conference call July 28 following the release of the results. Presenting the earnings results and guidance will be MDU Resources’ Chairman of the Board and Chief Executive Officer Martin A. White, President and Chief Operating Officer Terry D. Hildestad and Executive Vice President, Treasurer and Chief Financial Officer Vernon A. Raile.

The webcast will begin at 1 p.m. EDT and can be accessed at www.mdu.com. A webcast replay and audio replay will be available. The dial-in number for audio replay is (800) 642-1687 or (706) 645-9291, access code 2534001.

MDU Resources Group, Inc., a member of the S&P MidCap 400 index, provides value-added natural resource products and related services that are essential to energy and transportation infrastructure. MDU Resources includes natural gas and oil production, construction materials and mining, domestic and international independent power production, natural gas pipelines and energy services, electric and natural gas utilities, and construction services. For more information about MDU Resources, see the company's Web site at www.mdu.com or contact the Investor Relations Department at investor@mduresources.com

Contacts:

Phyllis A. Rittenbach
Director of Investor Relations
(701) 530-1057