Diagnosed with lung cancer in 1993, Mountjoy qualified for the World Championship at the age of 50, just weeks before having a lung surgically removed. He continued to play professionally until 1997, and he was coach to the United Arab Emirates snooker association between 1997 and 1999 and appeared sporadically at the World Snooker Championship until 2002. Mountjoy died in February 2021 after a stroke.