The relation between the electrocardiographic manifestation and the subjective symptoms accompanying organophosphate pesticide exposure caused by aerial spray was investigated. The study included 39 patients with a diagnosis of organophosphate poisoning, who visited A-clinic within 24h of exposure to aerial spray of organophosphate pesticide in Gumma Prefecture, from July 2001 to September 2001. Ages ranged from 3 to 82 years. Thirty-five patients were female. Three were diagnosed as severe, 11 moderate, and 25 mild, judged from the score of subjective symptoms. Electrocardiographic abnormalities were bradycardia (<50) 2; prolonged PQ interval 4; prolonged QTc interval (>430ms) 22; nonspecific ST-T change 35; supraventricular arrhythmia 13; and ventricular premature complex with R on T 1. Prolonged QTc interval developed in 2-3 severe cases, 4-11 moderate cases, and 16-25 mild cases. QT prolongation, ST-T change and arrhythmia were detected for some patients exposed to organophosphate by aerial spray.