It is an important rail link in the south and east of the canton of St. Gallen and follows the left bank of the Walensee and the Seeztal.

In 1961, the double-track Kerenzerberg Tunnel was opened, replacing the one-track section along the Walensee west of Murg.

While the InterCity trains predominantly consist of IC2000 push-pull sets propelled by class SBB Re 460 locomotives, there are also locomotive-hauled trains consisting of standard coaches (Einheitswagen) and (partly former) Eurocity coaches hauled by locomotives of classes Re 420 or Re 460.

The InterRegios were converted to Stadler KISS (RABe 511) at the end of 2013 and they no longer continue through Zurich to/from Basel, but they also stop in Walenstadt.

Instead of NPZ push-pull trains, which ran from Ziegelbrücke to Chur, the line was served by S4 service of St. Gallen S-Bahn, operated by Südostbahn (SOB) using Stadler Flirt sets, and stops at all the stations between Ziegelbrücke and Sargans.

Some S2 services of Zurich S-Bahn continue from Ziegelbrücke to Unterterzen (without stopping at the intermediate stations).

Freight traffic is heavy between Sargans and Buchs, because this is the transit route to the Vorarlberg and to the rest of Austria.