Morbidity and mortality of snake bites are said to be .the highest in Indo Pakistan subcontinent and in South East Asia Poisonous snakes belong to the following families (a) Viperidae or true vipers possess single large fang on short and otherwise toothless maxillae, permitting the fang to be erected or folded against the roof of the mouth. (b) Crotilelidae or pit vipers : It has a deep pit line with sensitive beat receptors situated between the eyes and the nostrils (c) Elapidae They are represented by coral snakes and cobras, these snakes have fixed fangs on the exterior ends of the maxillae. The fangs may be followed by solid teeth (d) Colubridae, family includes most of the world snakes about 2, 500 spp. (e) HydroVhidae These are marine snakes having fixed fangs on the interior ends of the maxillae, fangs may be followed by solid teeth. Among human beings snake bites are common during night. Snake bites are generally increased during the hotter months of the year, this is due to greater activity and vigour of the reptiles. During hot weather people sleep in the open on mats on the ground, which increases exposure to snake bites.