Methyl parathion is an organophosphorus (OP) insecticide with insecticidal properties derived from acetylcholinesterase (AChE) inhibition; this same property is also the root of its toxicity in humans. Poisoning with methyl parathion leads to cholinergic overstimulation with signs of toxicity including sweating, dizziness, vomiting, diarrhea, convulsions, cardiac arrest, respiratory arrest, and, in extreme cases, death. Reports of methyl parathion intoxication, usually seen only in field pesticide applicators, have increased throughout the United States as a result of unauthorized application of methyl parathion inside homes. The health concerns of the use of methyl parathion have resulted in cancellation of its use in most food crops in the United States. This review examines the well-documented neurotoxicity of methyl parathion as well as effects on other organ systems.