Organophosphate pesticides are used in agriculture to protect plants and livestock from pests so as to increase food yield. They are also used to control household and structural pests. Organophosphate pesticides inhibit acetylcholinesterase, preventing the break-down of acetylcholine in the nervous system which leads to the accumulation of acetylcholine in nerve endings resulting in paralysis. Information on organophosphate pesticides, mechanism of action of organophosphate chemicals, organophosphate toxicity, biological monitoring, and regulation of pesticides was obtained from other published articles, textbooks, and relevant internet sites. Studies have shown that there is a link between sensorimotor and cognitive impairments to organophosphate exposure as well as a link between affective disorders, depression, and suicide to the acute and chronic exposure to organophosphate insecticides in humans. Although being used as a pesticide and an insecticide, organophosphate chemicals pose a huge danger to health and as such, there should be general public awareness on its health risk with continuous and unguarded exposure to it.