We report on two patients with a history of chronic exposure to organochlorine insecticides who developed clinical and electromyographic signs and symptoms of chronic motor neuron disease. Measurements of aldrin, lindane and heptachlor confirmed the intoxication. We emphasize the importance of searching for toxic and environmental factors in cases of motor neuron disease especially in Third World countries, where workers usually wear no adequate protective equipment.Department of Neurology Faculty of Medicine, 18.610 Botucatu SPUNIV ESTADUAL PAULISTA JULIO MESQUITA FILHO,FAC MED,DEPT NEUROL & PSYCHIAT,BOTUCATU,BRAZIL