洛伊萨赫河是中欧的河流，流经德国和奥地利，发源自北莱姆斯通阿尔卑斯山脉，最终注入伊萨尔河，河道全长114公里，河畔城镇有加尔米施-帕滕基兴。

The Loisach is a river that flows through Tyrol, Austria and Bavaria, Germany. Its name is Celtic in origin, from Proto-Celtic *lawo and *iskā, both of which mean "water."

The Loisach is a 114 km long left tributary to the Isar. The source of the Loisach is near Ehrwald in Austria. The Loisach flows past Garmisch-Partenkirchen and into the Kochelsee. At the Kochelsee the water that was diverted from the upper river Isar for power generation at the Walcheseekraftwerk joins the Loisach. The Loisach then flows out of Kochelsee and joins the Isar at Wolfratshausen. A canal joins the Isar and the Loisach returning the water diverted for power generation to the Isar before Wolfratshausen to reduce the risk of flooding in the town.