Chemical and biological agents have been used as weapons of mass destruction for a long time and presents as a serious threat to mankind. They have been used in many great wars and terrorist attacks with devastating results. The knowledge about these weapons of mass destruction is crucial to health care providers. Early recognition of the clinical characteristics of poisoning as a result of these chemical and biological agents is important to initiate appropriate therapy and minimizing casualties. Neurophysiological investigations when integrated with clinical features are helpful in early identification of some of these agents, especially when serological confirmation is not rapidly available. In this review, we have focused on chemical and biological weapons, which affect the nervous system and the role of clinical neurophysiology in such conditions.