| Competition: | Campeonato Paulista – Série A1 |
| Season: | 1991 |
| Winners: | São Paulo |
| Relegated: | São Bento |
| Continentalcup1: | Copa do Brasil |
| Continentalcup1 Qualifiers: | Corinthians Palmeiras |
| League Topscorer: | Raí (São Paulo) – 20 goals |
| Biggest Home Win: | São Paulo 5–0 São José (October 12, 1991) Bragantino 5–0 Ituano (October 20, 1991) |
| Biggest Away Win: | Catanduvense 0–5 São Paulo (September 18, 1991) |
| Highest Scoring: | São Paulo 5–2 Marília (August 7, 1991) União São João 4–3 Ponte Preta (August 18, 1991) Santo André 4–3 Noroeste (October 23, 1991) |
| Matches: | 390 |
| Total Goals: | 756 |
| Prevseason: | 1990 |
| Nextseason: | 1992 |
The 1991 Campeonato Paulista da Primeira Divisão de Futebol Profissional[1] was the 90th season of São Paulo's top professional football league. São Paulo won the championship for the 17th time. São Bento was relegated.[2]
The twenty-eight teams competing in the championship were divided into two groups of fourteen teams. The Green Group comprised the teams that had qualified to the Third Phase and the winners of the Second Phase's two groups in the previous year, and the Yellow Group comprised other the ten teams that had been eliminated in the Second Phase, and the four teams that had been promoted from the second level.[3] The bottom team in the Yellow Group would be relegated.
The Second phase's eight teams were divided into two groups of four, with every team playing twice against the teams of its own group and the winners of each group qualifying to the Finals.
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