The Simplon railway line is a railway line that links Lausanne in Switzerland and Domodossola in Italy, via Brig. The 20 km long Simplon Tunnel (opened 1906) is a major part of it.
Together with the northern Lötschberg railway line it forms the second most important trans-Alpine railway line in Switzerland about 240 km west of the Gotthard line.
It is foreseen that ETCS level 2 will be installed on the line between Lausanne and Brig before 2022.
Freight trains are running on the line.
ETR 610-stock provides services between Geneva and Venice. The "Thello" night-service from Paris to Venice is using this former Simplon-Orient-Express track too.