The 1966 Grand Prix motorcycle racing season was the 18th F.I.M. Road Racing World Championship Grand Prix season. The season consisted of twelve Grand Prix races in six classes: 500cc, 350cc, 250cc, 125cc, 50cc and Sidecars 500cc. It began on 8 May, with Spanish Grand Prix and ended with Japanese Grand Prix on 17 October.
Honda stepped up their racing program with a new four-cylinder 500cc bike, as well as bikes in the four smaller classes. Despite Honda's increased efforts, Suzuki would claim the 50cc title with Hans-Georg Anscheidt winning the championship from Honda's Luigi Taveri at the last race of the season in Japan. Yamaha would battle Honda all season for the 125 crown, each factory taking five wins, with Honda's Taveri taking the title from Yamaha's Bill Ivy.
Mike Hailwood, having left the MV Agusta team to ride for Honda, stormed to the 250 crown, winning the first eight races of the season, as Phil Read struggled with Yamaha's new v-four race bike. Hailwood would make it a double when he also claimed the 350 class ahead of MV Agusta's Giacomo Agostini. Honda's plan was for Jim Redman to lead their 500 class campaign before he retired. All started well with Redman winning the first two races of the year however, Honda's hopes were dashed when he crashed in the rain in Belgium and broke his wrist. This gave Agostini the championship lead, which he held despite Hailwood taking three of the last six races. Honda took some consolation by winning all five constructor's titles for a clean sweep.
Points were awarded to the top six finishers in each race. Only the best of four were counted on 50cc championships, best of five in 350cc and 500cc championships, best of six in 125cc and 250cc championships, while in the Sidecars, only the best of three races were counted.
| Bold – Pole Italics – Fastest Lap |
| Place | Rider | Number | Country | Machine | Points | Wins | |
|---|---|---|---|---|---|---|---|
| 1 |  Mike Hailwood | United Kingdom | Honda | 48 | 6 | ||
| 2 |  Giacomo Agostini | Italy | MV Agusta | 42 | 3 | ||
| 3 | Renzo Pasolini | Italy | Aermacchi | 17 | 0 | ||
| 4 | Frantisek Stastny | Czechoslovakia | Jawa | 13 | 0 | ||
| 5 | Gustav Havel | Czechoslovakia | Jawa | 12 | 0 | ||
| 6 | Alberto Pagani | Italy | Aermacchi | 11 | 0 | ||
| 7 | Heinz Rosner | East Germany | MZ | 10 | 0 | ||
| 8 | Phil Read | United Kingdom | Yamaha | 8 | 1 | ||
| 9 |  Jack Ahearn | Australia | Norton | 8 | 0 | ||
| 10 | Bruce Beale | Rhodesia | Honda | 7 | 0 | ||
| 11 | Tarquinio Provini | Italy | Benelli | 6 | 0 | ||
| = | Peter Williams | United Kingdom | AJS | 6 | 0 | ||
| = | Bill Ivy | United Kingdom | Yamaha | 6 | 0 | ||
| 14 | Silvio Grassetti | Italy | Bianchi | 6 | 0 | ||
| 15 | Jim Redman | Rhodesia | Honda | 4 | 0 | ||
| = | Tommy Robb | United Kingdom | Bultaco | 4 | 0 | ||
| = | Chris Conn | United Kingdom | Norton | 4 | 0 | ||
| 18 | Gilberto Milani | Italy | Aermacchi | 3 | 0 | ||
| = | Stuart Graham | United Kingdom | AJS | 3 | 0 | ||
| = | Kel Carruthers | Australia | Norton | 3 | 0 | ||
| = | Byron Black | United Kingdom | Honda | 3 | 0 | ||
| 22 | Frantisek Bocek | Czechoslovakia | Jawa | 3 | 0 | ||
| 23 | Dave Simmonds | United Kingdom | Honda-Norton | 2 | 0 | ||
| = |  Kenzo Muromachi | Japan | Honda | 2 | 0 | ||
| 25 | John Blanchard | United Kingdom | AJS | 1 | 0 | ||
| = | Joe Dunphy | United Kingdom | Norton | 1 | 0 | ||
| = |  Kent Andersson | Sweden | Husqvarna | 1 | 0 |
| Place | Rider | Number | Country | Machine | Points | Wins | |
|---|---|---|---|---|---|---|---|
| 1 |  Luigi Taveri | Switzerland | Honda | 46 | 5 | ||
| 2 | Bill Ivy | United Kingdom | Yamaha | 40 | 4 | ||
| 3 | Ralph Bryans | United Kingdom | Honda | 32 | 0 | ||
| 4 | Phil Read | United Kingdom | Yamaha | 29 | 1 | ||
| 5 |  Hugh Anderson | New Zealand | Suzuki | 15 | 0 | ||
| 6 | Yoshimi Katayama | Japan | Suzuki | 14 | 0 | ||
| 7 | Frank Perris | United Kingdom | Suzuki | 10 | 0 | ||
| 8 | Akiyasu Motohashi | Japan | Yamaha | 5 | 0 | ||
| 9 |  Mike Duff | Canada | Yamaha | 4 | 0 | ||
| = | Mitsuo Itoh | Japan | Suzuki | 4 | 0 | ||
| 11 | Tommy Robb | United Kingdom | Yamaha | 3 | 0 | ||
| 12 | Francesco Villa | Italy | Montesa | 2 | 0 | ||
| = | Hans-Georg Anscheidt | West Germany | Suzuki | 2 | 0 | ||
| = | Peter Williams | United Kingdom | EMC | 2 | 0 | ||
| 15 |  José Medrano | Spain | Bultaco | 1 | 0 | ||
| = | Herbert Mann | West Germany | MZ | 1 | 0 | ||
| = | Mike Hailwood | United Kingdom | Honda | 1 | 0 | ||
| = | Friedhelm Kohlar | East Germany | MZ | 1 | 0 | ||
| = | Hartmut Bischoff | East Germany | MZ | 1 | 0 | ||
| = | Walter Scheimann | West Germany | Honda | 1 | 0 | ||
| = | Yasuharu Yuzawa | Japan | Yamaha | 1 | 0 |
| Place | Rider | Number | Country | Machine | Points | Wins | |
|---|---|---|---|---|---|---|---|
| 1 | Hans-Georg Anscheidt | West Germany | Suzuki | 28 | 2 | ||
| 2 | Ralph Bryans | United Kingdom | Honda | 26 | 1 | ||
| 3 | Luigi Taveri | Switzerland | Honda | 26 | 2 | ||
| 4 | Hugh Anderson | New Zealand | Suzuki | 16 | 0 | ||
| 5 | Yoshimi Katayama | Japan | Suzuki | 10 | 1 | ||
| 6 | Barry Smith | Australia | Derbi | 3 | 0 | ||
| = | Ernst Degner | West Germany | Suzuki | 3 | 0 | ||
| = | Mitsuo Itoh | Japan | Suzuki | 3 | 0 | ||
| 9 | Angel Nieto | Spain | Derbi | 2 | 0 | ||
| = | Oswald Dittrich | West Germany | Kreidler | 2 | 0 | ||
| = | Brian Gleed | United Kingdom | Honda | 2 | 0 | ||
| = | Tommy Robb | United Kingdom | Bridgestone | 2 | 0 | ||
| 13 |  Cees van Dongen | Netherlands | Kreidler | 1 | 0 | ||
| = | Isao Morishita | Japan | Bridgestone | 1 | 0 | ||
| = | Dave Simmonds | United Kingdom | Honda | 1 | 0 | ||
| = | André Roth | Switzerland | Derbi | 1 | 0 | ||
| = | Jack Findlay | Australia | Bridgestone | 1 | 0 |
Edy Lenz
György Kurucz
Byron Black
Ian Burne
Stan Adams
Lars Skjelfoss