The 2003 1. divisjon season kicked off on 13 April 2003, and the final round was played on 1 November 2003.
Ham-Kam were promoted to the 2004 Tippeligaen as 1. divisjon winners, along with Fredrikstad who finished second.
Ham-Kam will be playing in the top division for the first time since 1995, while Fredrikstad returned for the first time since 1975.
As in previous seasons, there was a two-legged promotion play-off at the end of the season, between the third-placed team in the 1. divisjon (Sandefjord) and the twelfth-placed team in the Tippeligaen (Vålerenga).
Vålerenga kept their spot in the Tippeligaen, beating Sandefjord 5-3 on aggregate.