Dessauer, H. C., D. F. Gartside, and R. G. Zweifel (Department of Biochemistry, Louisiana State University School of Medicine, New Orleans, LA 70112, and Department of Herpetology, American Museum of Natural History, New York, NY 10024) 1977. Protein electrophoresis and the systematics of some New Guinea hylid frogs (genus Litoria). Syst. Zool. 26:426–436.—Samples of 13 nominal species of the more than 50 recorded from New Guinea were collected at eight localities. Comparative data from nine proteins studied in all species indicate wide biochemical divergence among species, in concordance with morphological evidence, and suggest the presence of two distinct lineages. Biochemical evidence supports the recognition of two previously described pairs of sibling species and suggests that a third cryptic species may exist in one of these pairs. Litoria infrafrenata, a series for which no morphological variation of consequence in New Guinea has been recorded, shows population differentiation in proteins. Parameters of genetic variation in the species were estimated as: Ā = 1.62, P = 0.50, H = 0.073. In contrast, L. iris, a species with marked color pattern polymorphism, shows little variation in proteins. [Electrophoresis; Hylidae; Litoria.]