A case of possible organophosphate-induced parkinsonism is presented. The patient was a crop duster with numerous episodes of acute organophosphate intoxication and chronic organophosphate exposure. The etiology of parkinsonism is discussed in terms of a balance hypothesis between cholinergic and dopaminergic neurotransmission in the striatum. A possible relationship between chronic organophosphate exposure and alterations in central cholinergic or dopaminergic activity is suggested. The course of this patient raises the possibility that agricultural workers may be at risk for the late development of parkinsonism.