The Leoganger Ache is a river of Salzburg, Austria, a left tributary of the Saalach.
The Leonganger Ache drains the valley of the same name, the Leoganger Tal. It originates near the border with Tyrol in Hütten, municipality of Leogang, at a height of out of its two headstreams:
It flows from west to east and ist about long, including the .
After half its way it passes through the municipality of Leogang. The Leoganger Valley falls openly and gently into the Saalfelden Basin. Northwest of Saalfelden, in the parish of Uttenhofen, the Leoganger Ache discharges into the Saalach; at a triple confluence with the Urslau.
Its northern, right hand tributaries comprise several mountain streams that drain the limestone massif of the Leogang Mountains (the and empty into the , the from Birnhorn joins at Leogang and the at Ecking). From the Slate Alps the main streams are the (with the from the and the from the Halderbergkogel).
The "B 164 Hochkönig Road" (which comes from Bischofshofen via Dienten and Saalfelden) runs along the Leoganger Valley over the Grießen Pass and via Fieberbrunn to St. Johann in Tirol – it is the only internal Austria link between Tyrol and the east that does not cross a high Alpine pass, but is also linked to Salzburg via the Little German Corner.