Much biosystematic practice rests on the assumption that phenetic resemblances among populations and higher taxa reflect underlying genetic similarities. Through electrophoresis, it is now possible to measure genetic affinities among populations and species, using a variety of coefficients that quantify similarity across loci (Rogers, 1972; Nei, 1972). Consequently, theories treating the causes and significance of phenetic resemblances, the nature of biological species, and the genetics of speciation are being re-examined (Lewontin, 1974; Ayala, 1975; Avise, 1976). Biosystematists are finding themselves confronted with growing volumes of data on genetic resemblance generated by electrophoretic studies and with the task of shaping classifications and species criteria which accommodate these and more traditional lines of evidence (Mickevich and Johnson, 1976). This accommodation has been relatively easy because of general agreement between electrophoretic and taxonomic similarity (Avise, 1974). This study deals with genetic similarities within a species complex of salamanders of the genus Desmognathus that inhabits the ancient mountain ranges of the southern Appalachians. This complex is currently, if uneasily, treated as a single species, Desmognathus ochrophaeus. This and the other eight described species of Desmognathus form a morphologically uniform series which, like many other groups of plethodontid salamanders, possesses few taxonomically useful characters. The taxonomy of this genus rests heavily on tail shape, body size, color pattern, and ecology, all of which are difficult to quantify and vary intraspecifically. The result has been taxonomic instability, dissatisfaction with current species distinctions, and suspicion that unnamed forms exist. The taxonomy and systematics of such a group of organisms should be particularly benefitted by electrophoretic studies. This is especially true of D. ochrophaeus, one of the most taxonomically intractable members of its genus.