To survey the patterns of hearing impairment in patients of pesticide-poisoning, pure-tone and impedance audiometries were performed on 20 patients(40 ears) within one week after intoxication. And the following results were obtained : 1) Pure-tone audiometry revealed a moderately severe hearing loss of sensorineural type with descending form audiogram on the 3rd hospital day, but on the 7th day most of the cases revealed a mild hearing loss. 2) Impedance audiometry revealed type A tympanogram and absent acoustic reflex in the most cases and the static compliance fell in the range of 0.15cc~2.42cc on the 3rd hospital day.