Within each group, the teams would play a double round-robin to decide their league position.
The four group winners and the four runners-up then contested a play-off for the three promotion slots.
The four third-last placed teams would compete a play-out against the ninth relegation spot.
Urania Genève Sport win 2–0 on aggregate and continue to the finals.
[10] Urania Genève Sport win 7–4 on aggregate and are promoted to Nationalliga B.
[10] The play-off for the third promotion place was played on 16 June 1990 in Châtel-St-Denis.