Many organophosphate compounds are pesticides widely used for the control of insect vectors. They are not ideal agents because they lack target vector selectivity, and have caused severe toxicity and even death in humans and domestic animals. Their toxicity has been recognised since the 1930s, when they were also developed for use as chemical warfare agents. The mechanism of action of organophosphates has been determined in some depth; the understanding of the toxic effects resulting from the inhibition of cholinesterase activity, causing accumulation of acetylcholine at nerve endings has played a major part in providing a rationale for specific antidote treatment using atropine and oximes. However, the most suitable oxime for reactivation of cholinesterases has still not been established with certainty, although pralidoxime is widely recommended. Chronic toxicity, particularly the neuropathic effects, merits further study because it contributes substantially to the long term morbidity in cases of severe acute, or chronic, exposure. Prevention of potentially toxic organophosphate exposure, particularly amongst employees in industries manufacturing or using the compounds and in the most susceptible groups of the population, such as the young and the elderly, should be sought wherever possible. Government authorities should be encouraged to control organophosphate product licensing, manufacture, storage, import, methods of use and delivery, food contamination and disposal.