The 1956 Murray River flood involved the rising of waters in the Murray River and flooding of many towns in New South Wales, Victoria and South Australia. The flood was and still is considered the biggest flood in the recorded history of the Murray and described as "the greatest catastrophe in South Australia's history", although few lives were lost.

The Murray River is a river in Southeastern Australia. It is Australia's longest river at 2,508 km (1,558 mi) extent. Its tributaries include five of the next six longest rivers of Australia. Together with that of the Murray, the catchments of these rivers form the Murray–Darling basin, which covers about one-seventh the area of Australia. It is widely considered Australia's most important irrigated region.