The Oust (French pronunciation: [ust]; Breton: Oud) is a river in Brittany, France, right tributary of the Vilaine. It is 145 km (90 mi) long.^[1] Its source is in the hills between Corlay and Quintin. It flows generally southeast, through the following départements and towns:

• Côtes-d'Armor: Uzel
• Morbihan: Rohan, Josselin, Malestroit
• Ille-et-Vilaine: Redon

You can help expand this article with text translated from the corresponding article in French. (June 2019) Click [show] for important translation instructions. View a machine-translated version of the French article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing French Wikipedia article at [[:fr:Oust (rivière)]]; see its history for attribution. You may also add the template {{Translated|fr|Oust (rivière)}} to the talk page. For more guidance, see Wikipedia:Translation.

Quick Facts Location, Country ...

Oust
Oust river in Josselin
Location
Country	France
Physical characteristics
Source
• location	Brittany
Mouth
• location	Vilaine
• coordinates	47°37′50″N 2°5′49″W
Length	145 km (90 mi)
Basin size	3,630 km2 (1,400 sq mi)
Discharge
• average	25 m3/s (880 cu ft/s)
Basin features
Progression	Vilaine→ Atlantic Ocean

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The Oust flows into the river Vilaine in Redon. The part of the Oust between Rohan and Redon has been made navigable for small ships, and forms part of the Canal de Nantes à Brest.

The rivers Aff, Arz and Ninian are among its tributaries.