Ain is an approx. 200 km long river in eastern France. Its source is in the north-western Jura mountains. It flows south through the following départements and cities:

• Jura: Champagnole .
• Ain (named after the river): Pont-d'Ain .

The Ain flows into the river Rhône near Pont-de-Chéruy, approx. 40 km east of Lyon.