The Gastlosen (local Lè Gachtiyè pronounced as /le ɡaʃˈtije/) are a mountain range of the Swiss Prealps, lying between the cantons of Fribourg, Bern and Vaud. They form a 12adj=onNaNadj=on chain stretching from Jaun to Rougemont, culminating at the Dent de Savigny, elevation 2252m (7,388feet), just south-west of the Dent de Ruth, where the three cantonal borders meet.
The Trophée des Gastlosen is a competition of ski mountaineering which takes place in the area.