As a part of an inventory of bats in abandoned mines at the municipality of Guanaceví, Durango, Mexico, a sample of long-eared bats (genus Corynorhinus) was collected and ectoparasites were taken. Twenty-three specimens of Corynorhinus mexicanus Allen, 1916, and 18 of Corynorhinus townsendii (Cooper, 1937) were collected in four sampling periods coincident with the seasons. In total, 98 ectoparasites of 10 species and seven families were examined. Five species are recorded for the first time on C. mexicanus and four on C. townsendii. Macronyssus cyclaspis and Trichobius corynorhini had the highest frequency of infestation in both bats. Differences in number of arthropods per bat among seasons were nonsignificant for both species.