The 1979 British motorcycle Grand Prix was the eleventh event of the 1979 Grand Prix motorcycle racing season. It was held at the Silverstone Circuit, Northamptonshire in the United Kingdom.
The 500cc British Grand Prix would be one of the closest races in Grand Prix history. The race began with Barry Sheene, Kenny Roberts and Wil Hartog breaking away from the rest of the field. At the midpoint of the race, Hartog fell off the pace as Sheene and Roberts continued to battle for the lead. They continued to swap the lead throughout the 28 lap event with Roberts winning ahead of Sheene by a narrow margin of just three-hundreds of a second.
Minutes before the start of the race, Roberts' Yamaha blew a seal and sprayed the bike with oil. His crew managed to replace the seal in time but, Roberts went to the starting line with his gloves coated with oil, causing his hand to slip on the throttle during the race.
After an eleven-year absence from world championship racing, Honda returned to competition with the exotic, four-stroke NR500 ridden by riders Mick Grant and Takazumi Katayama. The motorcycle featured an engine with oval-shaped cylinders as well as a monocoque chassis. Both bikes retired from the race, Grant crashing out on the first turn after the bike spilled oil onto his rear tire. Katayama retired on the seventh lap due to ignition problems.