The Saarbahn is a regional Stadtbahn operating on the tram-train principle in the German state of the Saarland. It consists of a core line in Saarbrücken and Riegelsberg operating under tram operating procedures (BOStrab), connected to two lines that are operated under railway operating procedures (EBO), the Lebach–Völklingen railway to the north and the Saarbrücken–Sarreguemines railway in the south. Stadtbahn Saar GmbH is responsible for the infrastructure of the central section of line, while the outer tracks are operated by the national railway infrastructure companies, DB Netz AG in Germany and Réseau Ferré de France in France. Saarbahn GmbH is the train operating company for the whole system.
The route of the new line of the Saarbahn that was opened in central Saarbrücken in 1997 is essentially line 5 of the Saarbrücken tramway, which was closed in 1965. This line ran between Rastpfuhl and Schafbrücke and was the last line of the old metre-gauge network.
As of 2015, the current network operates on 44.0 kilometres (27.3 mi) of route, and serves 43 stations.