The South Western line is a narrow gauge railway line in the southern part of the state of Queensland, Australia. It junctions from the Southern line immediately south of Warwick station and proceeded westwards for a distance of 413 km to the town of Dirranbandi. A western extension to Boomie in New South Wales, approved by the Queensland Parliament in 1914, was never constructed. The Thallon-to-Dirranbandi section was closed on 2 September 2010.

The Southern railway line serves the Darling Downs region of Queensland, Australia. The 197-kilometre (122 mi) long line branches from the Western line at Toowoomba, 161 kilometres (100 mi) west of Brisbane, and proceeds south through Warwick and Stanthorpe to the New South Wales/Queensland state border at Wallangarra.