Illhaeusern (French pronunciation: [ilœjzəʁn] ⓘ; German: Illhäusern) is a commune in the Haut-Rhin department in Grand Est in north-eastern France.

The village stands at the confluence of the rivers Ill and Fecht.

Illhaeusern is famous for the Auberge de l'Ill, still one of the oldest 2-star establishments in France.

It was managed until 2008 by Paul Haeberlin, his son Marc took over after his death.

This Haut-Rhin geographical article is a stub.