The clinically important venomous snakes of Central and South America are pit vipers, family Crotalidae (previously named Viperidae), and include the genera Bothrops, Crotalus and Lachesis. Eighty-five per cent of bites are inflicted by Bothrops, 10% by Crotalus, 1% by Lachesis and the remainder by other venomous serpents, primarily coral snakes of the family Elapidae. The clinical presentations and recommended treatments are similar for the South American pit vipers and are therefore included in this paper.