A mixture of the potent neurotoxins tetrodotoxin (TTX) and chiriquitoxin (CHTX) was isolated from the skins of the male and the eggs of the female frog Atelopus chiriquiensis from Costa Rica. Tetrodotoxin was also found in the skin of both populations of Atelopus varius varius and Atelopus varius ambulatorious from Costa Rica. Zetekitoxin(ZTX) was isolated from Atelopus zeteki from Panama. The TTX, CHTX, and ZTX are potent neurotoxins and their toxicities are about the same (ca. 5-11 mug/Kg). The structural studies and biological activities of TTX, CHTX, and ZTX are described.