| Grand Prix: | Czechoslovak |
| Flag: | Czechoslovakia |
| Official Name: | Grand Prix CSFR-Brno[1] [2] [3] |
| Location: | Brno Circuit |
| Course Mi: | 3.357 |
| Course Km: | 5.403 |
| Race No: | 13 |
| Season No: | 15 |
| Date: | August 25 |
| Year: | 1991 |
| Pole Rider 500: | Wayne Rainey |
| Pole Rider 500 Country: | USA |
| Pole Time 500: | 2:03.358 |
| Fast Rider 500: | Wayne Rainey |
| Fast Rider 500 Country: | USA |
| Fast Time 500: | 2:03.266 |
| First Rider 500: | Wayne Rainey |
| First Rider 500 Country: | USA |
| Second Rider 500: | Mick Doohan |
| Second Rider 500 Country: | Australia |
| Third Rider 500: | John Kocinski |
| Third Rider 500 Country: | USA |
| Pole Rider 250 Country: | Germany |
| Pole Time 250: | 2:07.160 |
| Fast Rider 250: | Helmut Bradl |
| Fast Rider 250 Country: | Germany |
| Fast Time 250: | 2:07.052 |
| First Rider 250: | Helmut Bradl |
| First Rider 250 Country: | Germany |
| Second Rider 250 Country: | Spain |
| Third Rider 250 Country: | Italy |
| Pole Rider 125: | Loris Capirossi |
| Pole Rider 125 Country: | Italy |
| Pole Time 125: | 2:15.278 |
| Fast Rider 125: | Kazuto Sakata |
| Fast Rider 125 Country: | Japan |
| Fast Time 125: | 2:14.977 |
| First Rider 125: | Alessandro Gramigni |
| First Rider 125 Country: | Italy |
| Second Rider 125: | Loris Capirossi |
| Second Rider 125 Country: | Italy |
| Third Rider 125: | Gabriele Debbia |
| Third Rider 125 Country: | Italy |
The 1991 Czechoslovak motorcycle Grand Prix was the thirteenth round of the 1991 Grand Prix motorcycle racing season. It took place on the weekend of 23–25 August 1991 at the Masaryk Circuit located in Brno, Czechoslovakia.
Wayne Rainey on pole, his 6th for the season; Mick Doohan 0.1 seconds behind. Doohan gets the start from Rainey.
Doohan sets the fastest lap on the 8th, and Rainey is still with him. It's a big fight on the last lap, and Rainey gets the best of Doohan.
Rainey on how to beat Doohan: "I'd just sit on his wheel in the middle part of the race, and I'd make sure he could feel me, so he’d have to work his front tire harder, braking later and going deeper into the bends. As the tire got used up, his bike'd start to push and run out wide. Then I'd pass him and up the pace, and he couldn't stay with me."[4]
| Pos. | Rider | Team | Manufacturer | Time/Retired | Points | |||
|---|---|---|---|---|---|---|---|---|
| 1 |  Wayne Rainey | Marlboro Team Roberts | Yamaha | 47:32.169 | 20 | |||
| 2 |  Mick Doohan | Rothmans Honda Team | Honda | +3.204 | 17 | |||
| 3 | John Kocinski | Marlboro Team Roberts | Yamaha | +19.939 | 15 | |||
| 4 | Wayne Gardner | Rothmans Honda Team | Honda | +24.403 | 13 | |||
| 5 | Kevin Schwantz | Lucky Strike Suzuki | Suzuki | +25.039 | 11 | |||
| 6 | Juan Garriga | Ducados Yamaha | Yamaha | +33.195 | 10 | |||
| 7 |  Didier de Radiguès | Lucky Strike Suzuki | Suzuki | +52.768 | 9 | |||
| 8 | Eddie Lawson | Cagiva Corse | Cagiva | +53.356 | 8 | |||
| 9 | Sito Pons | Campsa Honda Team | Honda | +1:22.765 | 7 | |||
| 10 | Doug Chandler | Roberts B Team | Yamaha | +1:24.755 | 6 | |||
| 11 | Eddie Laycock | Millar Racing | Yamaha | +1 Lap | 5 | |||
| 12 | Michael Rudroff | Rallye Sport | Honda | +1 Lap | 4 | |||
| 13 | Cees Doorakkers | HEK-Baumachines | Honda | +1 Lap | 3 | |||
| 14 | Hans Becker | Team Romero Racing | Yamaha | +1 Lap | 2 | |||
| 15 | Simon Buckmaster | Padgett's Racing Team | Suzuki | +1 Lap | 1 | |||
| 16 |  Josef Doppler | Doppler Racing | Yamaha | +1 Lap | ||||
| 17 | Nicholas Schmassman | Schmassman Technotron | Honda | +2 Laps | ||||
| Ret | Martin Trösch | MT Racing | Honda | Retirement | ||||
| Ret |  Andreas Leuthe | Librenti Corse | Suzuki | Retirement | ||||
| DNS |  Jean Philippe Ruggia | Sonauto Yamaha Mobil 1 | Yamaha | Did not start | ||||
| DNS | Adrien Morillas | Sonauto Yamaha Mobil 1 | Yamaha | Did not start | ||||
| DNQ |  Helmut Schutz | Rallye Sport | Honda | Did not qualify | ||||
| DNQ |  Vincenzo Cascino | Vogt Honda | Honda | Did not qualify | ||||
| Sources:[5] [6] | ||||||||