Recruited from Victorian Football Association (VFA) club Springvale, Dempster spent much of his time at South Melbourne in defence but was also used up forward to good effect later in his VFL career.
After making his debut as a 17-year-old in 1972, Dempster played only 25 games in his first four seasons, but made 18 appearances in 1976.
[1] He then ruptured a medial ligament in his knee during the opening round of the 1978 season and missed the rest of the year as a result.
[1] Dempster would go on to become a premiership-winning player with Springvale and was still competing for the club in the early 1990s, captaining them in 1991.
He is the father of Sydney and St Kilda footballer Sean Dempster, who was drafted under the father–son rule.