The Ulster Derby is a flat handicap horse race in Northern Ireland open to three-year-old horses. It is run at Down Royal over a distance of 1 mile and 4 furlongs (2,414 metres), and it is scheduled to take place each year in June.The event was established in 1936, and it was originally restricted to three-year-olds. For a period it was contested over 1 mile, 4 furlongs and 68 yards.