Adrian Moorhouse achieved his first major international success when he won the 200 metres breastbone at the 1983 European Championships. The following year he made his Olympic début, finishing fourth in the 100 metres breaststroke and winning the B final in the 200 metres breaststroke at Los Angeles. Wins in the 100 metres breaststroke at the 1985 and 1987 European Championships followed and at the 1988 Olympics he won the gold medal by the narrowest of margins over Károly Gűttler of Hungary. In addition to his successes at the Olympic Games and European Championships, Moorhouse won individual gold medals in 1982, 1986 and 1990 Commonwealth. Although he constantly threatened the world record, he seemed destined to miss adding this honor to his impressive list of achievements until in the heats of the 1989 European Championships in Bonn he clocked 1:01.49 and shaved 0.16 seconds off the world 100 metre breaststroke record set by the American Steve Lundqvist at the 1984 Olympic Games. Moorhouse could not make a further improvement on his record in the final but he duly took the gold medal, his fourth successive European title. At the 1990 Commonwealth Games in Auckland, he equaled the world record he had set in Bonn and later that year, at the National Championships at Crystal Palace, he equaled his own world record for a second time.