The revision of Apios in North America is based on morphological analysis of herbarium specimens as well as field and greenhouse observations. The genus is herein recognized as consisting of two distinct species in North America. Apios priceana was described by Robinson in 1898. Currently it is listed as threatened by the United States Fish and Wildlife Service and is known from 47 populations in 22 counties in Alabama, Kentucky, Mississippi and Tennessee. The other species, A. americana, widely distributed in eastern North America, was first described by Cornut in 1633 and has been regarded as consisting of six infraspecific taxa, which are not recognized in the present treatment. Demarcation is based primarily on reproductive features as vegetative characteristics, both within and between species, exhibits a significant amount of variation. In addition to the taxonomic descriptions, dichotomous keys, illustrations and distribution maps are presented for each species.