1981 San Marino Grand Prix
- Round
- 4 of 1981
- Circuit
- Autodromo Enzo e Dino Ferrari
- Location
- Imola, Italy
- Dates
- —
- Format
- Standard weekend
- Winner
- Nelson Piquet
- Constructor
- Brabham
- Entrant
- Brabham-Ford
- Pole position
- Gilles Villeneuve
- Fastest lap
- Gilles Villeneuve
- Confidence
- reference
Classification
| Pos | Driver | Constructor | Grid | Laps | Points | Status |
|---|---|---|---|---|---|---|
| 1 | Nelson Piquet | Brabham | 5 | 60 | 9 | — |
| 2 | Riccardo Patrese | Arrows | 9 | 60 | 6 | — |
| 3 | Carlos Reutemann | Williams | 2 | 60 | 4 | — |
| 4 | Héctor Rebaque | Brabham | 13 | 60 | 3 | — |
| 5 | Didier Pironi | Ferrari | 6 | 60 | 2 | — |
| 6 | Andrea de Cesaris | McLaren | 14 | 60 | 1 | — |
| 7 | Gilles Villeneuve | Ferrari | 1 | 60 | — | — · fastest lap |
| 8 | Rene Arnoux | Renault | 3 | 59 | — | — |
| 9 | Marc Surer | Ensign | 21 | 59 | — | — |
| 10 | John Watson | McLaren | 7 | 58 | — | — |
| 11 | Patrick Tambay | Theodore | 16 | 58 | — | — |
| 12 | Alan Jones | Williams | 8 | 58 | — | — |
| 13 | Slim Borgudd | ATS | 24 | 57 | — | — |
| DNQ | Siegfried Stohr | Arrows | — | — | — | DNQ |
| DNQ | Derek Daly | March | — | — | — | DNQ |
| DNQ | Jan Lammers | ATS | — | — | — | DNQ |
| DNQ | Chico Serra | Fittipaldi | — | — | — | DNQ |
| DNQ | Derek Warwick | Toleman | — | — | — | DNQ |
| DNQ | Brian Henton | Toleman | — | — | — | DNQ |
| DNF | Alain Prost | Renault | 4 | 3 | — | Gearbox |
| DNF | Jacques Laffite | Ligier | 10 | 7 | — | Suspension |
| DNF | Bruno Giacomelli | Alfa Romeo | 11 | 28 | — | Collision |
| DNF | Mario Andretti | Alfa Romeo | 12 | 26 | — | Gearbox |
| DNF | Keke Rosberg | Fittipaldi | 15 | 14 | — | Engine |
| DNF | Michele Alboreto | Tyrrell | 17 | 31 | — | Collision |
| NC | Jean-Pierre Jabouille | Ligier | 18 | 45 | — | NC |
| DNF | Eddie Cheever | Tyrrell | 19 | 28 | — | Collision |
| DNF | Beppe Gabbiani | Osella | 20 | 31 | — | Collision |
| DNF | Miguel Ángel Guerra | Osella | 22 | 0 | — | Accident |
| DNF | Eliseo Salazar | March | 23 | 38 | — | Spun off |