The Bex–Villars–Bretaye Railway is a metre gauge railway line operating between the towns of Bex and Villars-sur-Ollon and the Col de Bretaye mountain pass, situated in the Chablais region of southwest Switzerland. It is, in fact, two railways, one mixed adhesion and rack worked between Bex and Villars-sur-Ollon, the other, linking Villars to the Col de Bretaye being worked on the Abt rack system. Passengers making the full journey are required to change trains at Villars.

Bex is a municipality in the canton of Vaud, Switzerland, located in the district of Aigle. It is a few kilometers south of its sister town municipality of Aigle.