High Quality Content by WIKIPEDIA articles! The Australian Derby also known as AJC Derby, is a Group 1 Thoroughbred horse race run by the Australian Jockey Club (AJC) at Randwick Racecourse in Sydney, Australia. Open to three year olds, the race is held annually in the latter part of March or early April. The AJC says it is known as the top ranked event for three-year-olds in Australian and New Zealand race classifications.