The chronic effects of pesticide overexposure on the nervous system were reviewed and discussed. The peripheral nervous system (PNS) effects of organophosphate pesticides, which operated via cholinesterase inhibition, included paresthesias, weakness, foot and wrist drop, and paralysis. The peripheral neuropathy associated with organophosphate exposure was termed organophosphate induced delayed polyneuropathy (OPIDP). OPIDP generally developed 2 to 5 weeks after clinically severe intoxication with an organophosphate pesticide. Interference with the neuropathy target esterase enzyme appeared to be the biochemical mechanism of the organophosphate pesticides that caused OPIDP. The acute central nervous system (CNS) effects of organophosphate pesticides included concentration, vigilance, memory, information processing, psychomotor speed, and language impairment, anxiety, irritability, and depression. The chronic effects of organophosphate pesticide exposure were generalized cognitive impairment and personality changes. Case studies were cited which indicated that exposure to carbamates possibly induced adverse PNS and CNS effects. Organochlorine pesticides reportedly induced tremors, muscle weakness, ataxia, slurred speech, and incoordination, as well as cognitive and personality changes. Peripheral neuropathic alterations and behavior and cognitive changes were associated with exposure to heavy metal pesticides. Peripheral neuropathy and personality changes in humans were also associated with exposure to fumigants. Autonomic and peripheral nerve functioning was impaired following exposure to dithiocarbamate fungicides. The rodenticide vacor (53558251) reportedly induced acute diabetic ketoacidosis and peripheral neuropathy.