The S50 is a railway service that runs every hour between Biasca and Malpensa Aeroporto Terminal 1 in the Swiss canton of Ticino and the Italian state of Lombardy, respectively.

Treni Regionali Ticino Lombardia (TILO), a joint venture of Swiss Federal Railways and Trenord, operates the service.

[a] It uses the Ceneri Base Tunnel between Giubiasco and Lugano, bypassing the traditional Gotthard route.

South of Varese it runs express to Gallarate, complementing the half-hourly local service of Trenord's S5.

[7][8] On 9 June 2019 the S50 and S40 swapped southern termini, with the S50 operating through to Malpensa Aeroporto and the S40 terminating at Varese.