Les Appalaches ((in French) Municipalité régionale de comté des Appalaches) is a regional county municipality (RCM) in the Chaudière-Appalaches region in southeastern Quebec, Canada. It was established in 1982 from parts of the historic counties of Beauce, Frontenac, Mégantic, and Wolfe. The county seat and largest city is Thetford Mines.

The name of the RCM is linked to its location in the Appalachian Mountains with Mounts Adstock, Caribou, Oak, and Saint-Adrien being the highest. Until 2008, it was known as L'Amiante Regional County Municipality, because of the importance of asbestos mining in the region (amiante is French for "asbestos").

There are 19 subdivisions within the RCM:

Mother tongue from Canada 2016 Census

Language	Population	Pct (%)
French only	40,675	97.7%
English only	495	1.2%
Both English and French	145	0.3%
Other languages	325	0.8%

Highways and numbered routes that run through the municipality, including external routes that start or finish at the county border:

• Chemins Craig and Gosford Historic Route
• Serpentine-de-Coleraine Ecological Reserve (Saint-Joseph-de-Coleraine)
• Frontenac National Park (Adstock)
• Heritage Kinnear's Mills (Kinnear's Mills)
• Mount Adstock (Adstock)
• Musée minéralogique et minier de Thetford Mines (Thetford Mines)
• Thetford Mines Bike Path (Thetford Mines)

• List of regional county municipalities and equivalent territories in Quebec

• Commission de toponymie du Québec