Venomous reptiles are distributed in select habitats in temperate and tropical areas of the world with few geographical exceptions, and have adapted to not only terrestial existence, but to arboreal and aquatic environments as well. Venomous snakes are found in the families Colubridae (fixed and rear fanged snakes), Elapidae (fixed and front fang snakes), Hydrophiidae (sea snakes), Viperidae (Old World vipers) and Crotalidae (pit vipers). Venomous lizards are found in the United States and Mexico, and comprise the family Helodermatidae. Venom delivery systems and venom components show diversity, and greater appreciation of interspecies clinical effect is apparent in modern literature. First aid care for the bitten individual remains controversial, but most authorities now tend to minimize field procedures, especially those endeavors which may potentially damage tissue. The weight of evidence in the area of definitive therapy lies with the use of antivenin, although proponents of primary surgical intervention in crotalid envenomations have followings, particularly in the United States. Recent developments in "purification" of existing antivenins are promising, and attention to species-specific antivenin production, especially to the venoms of the crotalid species of the New World, is encouraged. Due to a growing international traffic in venomous animals for the purposes of research and supply of zoos and private reptile collections, knowledge of resources for assistance in bites of non-indigenous reptiles is a growing consideration.