Use of abandoned mines by Corynorhinus mexicanus and C. townsendii is documented for a sample of 25 mines in Guanaceví, Durango, Mexico, during 1 year. Presence–absence of bats was recorded, and significance of associations between bat presence and environmental and structural characteristics of mines was tested. Bats occupied 15 of 25 mines examined. Males and females were observed in low numbers, and scattered throughout mine workings. Mines were used as hibernation roosts in winter, and as day roosts and temporary night roosts during the rest of the year. A maternity colony of endemic C. mexicanus was observed in 1 mine. Temperature and adit length were significantly associated with bat occupancy. Bats were more commonly found in mines that were at least 50 m long, had temperatures <10°C in winter, and temperatures >16°C the rest of the year. Mines might be providing an alternative refuge for these species in heavily deforested habitats.