The Ailette (French pronunciation: [ɛlɛt]) is a 59.5 km (37.0 mi) long river in the Aisne department in eastern France. Its source is at Sainte-Croix. It flows generally west-northwest. It is a left tributary of the Oise into which it flows between Manicamp and Quierzy, 30 km (19 mi) northeast of Compiègne.

On most of its course, it shares its valley with the Canal de l'Oise à l'Aisne.

This list is ordered from source to mouth:

• Aisne: Sainte-Croix, Corbeny, Craonne, Bouconville-Vauclair, Chermizy-Ailles, Neuville-sur-Ailette, Cerny-en-Laonnois, Chamouille, Pancy-Courtecon, Colligis-Crandelain, Trucy, Chevregny, Monampteuil, Filain, Pargny-Filain, Urcel, Chavignon, Royaucourt-et-Chailvet, Chaillevois, Merlieux-et-Fouquerolles, Vaudesson, Pinon, Lizy, Anizy-le-Château, Vauxaillon, Landricourt, Leuilly-sous-Coucy, Jumencourt, Crécy-au-Mont, Coucy-le-Château-Auffrique, Pont-Saint-Mard, Guny, Champs, Trosly-Loire, Saint-Paul-aux-Bois, Pierremande, Bichancourt, Manicamp, Quierzy