The 18th BRDC International Trophy was a motor race, run to Formula One rules, held on 14 May 1966 at the Silverstone Circuit, England.

The race was run over 35 laps of the Silverstone Grand Prix circuit, and was won by Australian Jack Brabham in the Brabham-Repco BT19.

Regular front runners Ferrari and Lotus were both prepared with new vehicles, as was former World Champion Jack Brabham's eponymous team, fielding Australian Repco engines.

[2] BRM's new H16 engine was also slated to appear, but reliability problems resulted in Peter Arundell being forced to withdraw his Lotus-BRM prior to qualifying.

Despite qualifying an impressive third, Jochen Rindt's Cooper developed mechanical troubles and dropped him back to fifth by the end of the race.