The 1989–90 Campionato Sammarinese di Calcio season was the 5th season since its establishment. It was contested by 10 teams, and S.P. La Fiorita won the championship.
Regular season
Championship playoff
First round F.C. Domagnano 2-2 (pen 4-6) A.C. Libertas S.S. Montevito 0-1 S.S. Cosmos
Second round F.C. Domagnano 1-0 S.S. Montevito A.C. Libertas 2-1 S.S. Cosmos
Third round F.C. Domagnano 1-2 S.S. Cosmos A.C. Libertas 1-1 (pen 6-4) S.P. Tre Fiori
Fourth round S.S. Cosmos 1-1 (pen 5-4) S.P. Tre Fiori S.P. La Fiorita 4-0 A.C. Libertas
Semifinal A.C. Libertas 1-3 S.S. Cosmos
Final S.P. La Fiorita 1-0 S.S. Cosmos
References San Marino - List of final tables (RSSSF)