The 1939 Australian Grand Prix was a motor race held on the Lobethal Circuit in South Australia, Australia on 2 January 1939. The race had 17 starters and was held over 17 laps of the fourteen kilometre circuit, the longest ever used for the Grand Prix, for a race distance of 241 kilometres. The average speed was the fastest of any Australian Grand Prix prior to 1956, with race winner Alan Tomlinson averaging 84.00 mph.
The race was the eleventh Australian Grand Prix and the second since the 1938 revival of the Grand Prix. The Lobethal Circuit comprised three country roads in a roughly triangular formation, passing through the town of Lobethal and the nearby village of Charleston. The advantage of using these country roads was that, for the first time, the Grand Prix was held on a bitumen sealed surface instead of on dirt roads.
The race was won by relatively unknown Western Australian racer Allan Tomlinson driving a supercharged MG T. Bob Lea-Wright's Terraplane Special finished in second position ahead of Jack Phillips' Ford Special. The fastest actual time over the race distance was recorded by Jack Saywell driving an Alfa Romeo.
The entry of J O'Dea crashed at the Gumeracha turn late in the race and driver Vern Leech was killed almost instantaneously.
Later in 1939, Australia would declare war on the AXIS powers. As World War II enveloped Australia, motor racing wound down and would not resume until the mid-1940s. The Australian Grand Prix itself would be revived in 1947.