The 36 teams of the Swiss Football League (Nationalliga) were divided into two tiers.
Each team in each group played a double round-robin in the qualification phase.
The qualification stage of the NLA began on 25 July 1990 and was completed on 16 December.
The teams took half of the points (rounded up to complete units) gained in the qualification as bonus with them.
The two legged play-out against relegation between both second last placed teams was played on 1 and 8 June 1991.