Branchiobdellidans, or crayfish worms, are species-rich in the Appalachian area of the southeastern United States. Even so, the Great Smoky Mountains National Park (GSMNP) in the southern Appalachians has only one record of a branchiobdellidan species. As part of the All Taxa Biodiversity Inventory, we undertook a general survey of the branchiobdellidans in the GSMNP. Crayfish were collected from a total of 15 sites distributed across 11 watersheds in the GSMNP We identified a total of 10 species of branchiobdellidans: 1 species of Bdellodrilus, 1 species of Oedipodrilus, 2 species of Pterodrilus, 1 species of Xironodrilus, and 5 species of Cambarincola. The composition and number of species per site ranged from 0 to 6, and individual branchiobdellidan species occurrence ranged from 1 to 11 sites. Our results suggest that multiple factors affect distribution and occurrence on certain hosts. Study of specimens of Cambarincola holostomus Hoffman, 1963 enabled us to add new morphological characters to the description of this species. An intensive survey of watersheds and crayfish fauna in the GSMNP is necessary to understand the multiple factors affecting species distributions and host preferences and to facilitate conservation of both the symbionts and their hosts.