Biogenic amines and active polypeptides in the skin of Leptodactylus vilarsi from Ecuador are quite similar to the biogenic amines and active polypeptides in the skin of Leptodactylus dengleri from Panamá, but they differ from the biogenic amines and active polypeptides in the skin of Leptodactylus labyrinthicus (Misiones). Such a biochemical phyletic and evolutive trend shows a striking parallelism with the serological relationships within these Leptodactylus frogs as evidenced by the crossed precipitin tests.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Museo