Organophosphate poisoning is an important cause of poisonings. Organophosphate compounds are commonly used as agricultural insecticides. Thus, acute organo-phosphate pesticide poisoning is widespread in the developing countries. Organophosphate compounds inhibit acetylcholinesterase irreversibly and lead to accumulation of acetylcholine at synapses and plasma. The clinical effects are secondary to acetylcholine excess at cholinergic junctions, in the central nervous system, at nerve-muscle junctions, and at autonomic ganglia. Intermediate syndrome and acute cholinergic crisis are important complications of organophosphate poisonings, and these are the main causes of morbidity and mortality. The diagnosis is based on clinical and laboratory findings including cholinesterase levels. Treatment of organophosphate poisonings consists of supportive care, especially aimed at respiratory complications, and specific antidotal therapy including atropine (as an anti-cholinergic agent) and oximes (as cholinesterase reactivators), such as pralidoxime and obidoxime, but they have failed to improve outcomes in some cases. Recently, some other agents, such as clonidine, magnesium, fluoride and human plasma/ plasmapheresis has been investigated in management of organophosphate poisonings.