The Leutascher Ache (also: Leutasch) is a left tributary of the river Isar in Austria.It originates in the Tyrolean valley of Gaistal as a tailwater of the Igelsee, flows between the Wetterstein Range and the Mieming Range, swings northeast near Leutasch, runs through the Leutaschtal, a high valley, and discharges into the Isar after passing through the Leutasch Gorge near Mittenwald in Bavaria.