Nerve agents are extremely toxic chemicals that were first developed in secrecy before and during World War II primarily for military use. Related substances are used in medicine, in pharmacology, and for other purposes, such as insecticides, but they lack the potency of the military agents. Much of the basic knowledge about the clinical effects of nerve agents comes from research performed in the decades immediately following World War II. The military stockpiles of several major powers are known to include nerve agents, and the armamentaria of other countries are thought to contain them as well (see Chapter 4, The Chemical Warfare Threat and the Military Healthcare Provider). Because of the possibility of nerve agent use in future conflicts, military medical personnel should have some knowledge of these agents, their effects, and the proper therapy for treating casualties. Therapy is based on the administration of atropine, which interferes with receptor binding of acetylcholine at muscarinic but not nicotinic receptors, and the oxime 2-PAM Cl, which breaks the agent-enzyme bond formed by most agents. Assisted ventilation and other supportive measures are also required in severe poisoning.