The Adour (French pronunciation: [aduʁ] ; Basque: Aturri; Occitan: Ador) is a river in southwestern France. It rises in High-Bigorre (Pyrenees), in the commune of Aspin-Aure, and flows into the Atlantic Ocean (Bay of Biscay) near Bayonne. It is 308.3 kilometres (191.6 mi) long, of which the uppermost ca. 11 kilometres (6.8 mi) is known as the Adour de Payolle. At its final stretch, i.e. on its way through Bayonne and a short extent upstream, the river draws the border between the Northern Basque Country and Landes regions.

Départements and towns along the river include:

• Hautes-Pyrénées: Bagnères-de-Bigorre, Tarbes, Maubourguet
• Gers: Riscle
• Landes: Aire-sur-l'Adour, Dax, Tarnos
• Pyrénées-Atlantiques: Bayonne

The main tributaries of the Adour are, from source to mouth:

• Adour de Gripp (also Adour du Tourmalet, 15 km)
• Adour de Lesponne (19 km)
• Échez (64 km)
• Arros (130 km)
• Léez (56 km)
• Gabas (117 km)
• Midouze (151 km)
• Louts (86 km)
• Luy (154 km)
• Gave de Pau (191 km)
• Bidouze (82 km)
• Aran (48 km)
• Ardanabia (26 km)
• Nive (79 km)

• Commission Européenne—Natura 2000: Cartographie du Barthes de l'Adour—(in French) — maps of the Adour and Adour Basin.
• Natura 2000 Sites d'Intérêt Communautaire par la France: Barthes de l'Adour — (in French)
• Adour Archived 2014-11-10 at the Wayback Machine—(in French) — website homepage.
• European Commission: official Natura 2000 Network website— — "the centrepiece of EU nature & biodiversity policy."