Samples of the Notropis rubellus complex were collected from 33 localities in Kentucky and Tennessee during the late spring and early summer of 1998–2001. Based on nuptial coloration, scale and fin-ray counts, and body shape, two taxa were diagnosed and recognized as species in the study area. Notropis rubellus (Agassiz) occupies upland streams of the Ohio River basin upstream of the mouth of the Green River and in the Cumberland River drainage above Cumberland Falls. Notropis micropteryx (Cope) occurs in upland streams of the Cumberland River drainage downstream of Cumberland Falls and the Tennessee River and Green River drainages. This species differs from N. rubellus in having modally fewer circumferential scales (23–24 vs. 25–26), modally fewer scales below the lateral line (three vs. four), and less red on the dorsum of the head of nuptial males. Green River populations exhibit more mean scales below the lateral line and slightly more intense red than other N. micropteryx populations. Support for recognition of these taxa as evolutionary species includes zoogeographic evidence in addition to the array of morphological characters.