Loudun (/luːˈdʌn/; French pronunciation: [lu.dœ̃]; Poitevin: Loudin) is a commune in the Vienne department and the region of Nouvelle-Aquitaine, western France.

It is located 30 km (19 mi) south of the town of Chinon and 25 km to the east of the town Thouars.

The area south of Loudun is the place of origin of a significant portion of the Acadians, one of the early settlers of New France in Canada.

[3] Loudun, an ancient town, contains numerous old streets, buildings and monuments of which five are Government-listed monuments.

It is also the location of a vicus type archaeological site.