<i>Leptodactylus ocellatus</i> and <i>L. chaquensis</i>, two closely related species of Argentine anurans, were compared by an electrophoretic study of the serum protein patterns. Significant differences were obtained between the two species, both in the comparison of allopatric as well as sympatric populations.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Museo