1990-91 Primera B Nacional

The 1990-91 Argentine Primera B Nacional was the 5º season of second division professional of football in Argentina. A total of 22 teams competed; the champion and runner-up were promoted to Argentine Primera División.

Quilmes was declared champion and was automatically promoted to Primera División, and the teams placed 2º to 10º qualified for the Second Promotion Playoff.

1: Did not qualify for the Second Promotion Playoff as it was involved in Relegation.

2: 8 points deducted for violence acts.

The Second Promotion Playoff or Torneo Reducido was played by the teams placed 2º to 11º in the overall standings: Atlético Tucumán (2º), who entered in the Semifinals, Belgrano (3º), who entered in the Second Round, and in the first round entered San Martín (T) (5º), Banfield (6º), Almirante Brown (7º), Instituto (8º), Douglas Haig (9º), Deportivo Morón (10º) and Atlético de Rafaela (11º), (Cipolletti (4º) did not qualify because it was relegated). In the first round also participated the champion of Primera B Metropolitana: Central Córdoba (R), and Nueva Chicago and San Martín (SJ), both winners of Zonales Noroeste y Sureste from Torneo del Interior. The winner was promoted to Primera División.