Aquatic and semiaquatic beetles in the families Dytiscidae, Gyrinidae, Haliplidae, Helophoridae, Hydraenidae, Hydrophilidae, and Noteridae of the Great Smoky Mountains National Park (GSMNP) were sampled from 2003 to 2006. Current and historic literature as well as the insect collections at GSMNP, Illinois Natural History Survey, Smithsonian Institution, and University of Tennessee were examined for GSMNP records. This is the first comprehensive effort at surveying the aquatic and semiaquatic beetles of GSMNP. A total of 115 species were recorded: 46 Dytiscidae, 7 Gyrinidae, 5 Haliplidae, 2 Helophoridae, 2 Hydraenidae, 2 Hydrochidae, 49 Hydrophilidae, and 2 Noteridae. Eighty species are reported from GSMNP for the first time. Hydaticus aruspex Clark, Hydrocolus deflatus, H. paugus, Liodessus affinis (Dytiscidae), and Dactylosternum abdominale (Hydrophilidae) are reported from Tennessee for the first time.