Abstract As a chemical weapon, G-series nerve agents are organophosphorus compounds that act by inhibition of cholinesterase enzyme and consequently overstimulation of cholinergic receptors. Inhalation of the vapor is the most common route of exposure, while the liquid forms are more readily absorbed through the skin. Respiratory failure and cardiac arrest are their deadliest effects, mediated by depression of respiratory and vasomotor centers in the central nervous system. The clinical presentations of poisoning are similar to but more severe than those of organophosphorus pesticides. According to the standard protocols for organophosphorus intoxication, clinical management and treatment of their poisoning should be measured.