The Jeker is a river in Belgium and in the Netherlands. It is a left-bank tributary to the river Meuse. The source of the Jeker is near the village of Geer, in the Belgian province of Liège. The river is approximately 54 kilometres long, of which about 50 kilometres is in Belgium and 4 kilometres in the Netherlands, where it flows into the river Meuse at Maastricht.
Places through which the Jeker passes include Waremme, Tongeren, Kanne, and Maastricht.