1991 Formula One season Drivers and constructors Drivers and constructors

| Entrant | Constructor_ | Chassis | Engine | Tyre | Driver | Rounds |
|---|---|---|---|---|---|---|
| Leyton House Racing | Leyton House - Ilmor | CG911 | Ilmor 2175A V10 | G | Maurício Gugelmin | All |
| Leyton House Racing | Leyton House - Ilmor | CG911 | Ilmor 2175A V10 | G | Ivan Capelli | 1-14 |
| Leyton House Racing | Leyton House - Ilmor | CG911 | Ilmor 2175A V10 | G | Karl Wendlinger | 15-16 |
| Automobiles Gonfaronaise Sportive | AGS - Ford | JH25 JH25B JH27 | Ford Cosworth DFR 3.5 V8 | G | Gabriele Tarquini | 1-13 |
| Automobiles Gonfaronaise Sportive | AGS - Ford | JH25 JH25B JH27 | Ford Cosworth DFR 3.5 V8 | G | Olivier Grouillard | 14 |
| Automobiles Gonfaronaise Sportive | AGS - Ford | JH25 JH25B JH27 | Ford Cosworth DFR 3.5 V8 | G | Stefan Johansson | 1-2 |