A great number of studies about noise-induced hearing loss have been published even in our country since the first report by Alberti in 1591. It has been shown that hearing loss caused by exposure to noise is prominent not only in present social development, but in new development of military equipments such as weapon and airplanes. The main cause of noise-induced hearing loss is exposure to noisy environment, but it is related to the duration of exposure, noise intensity and frsquency, age, sex, and individual susceptibility to noise. The authors performed audiological evaluations for 141 army pilots with concentration on the incidence, degree, symmetricity and subjective symptoms of noise-induced hearing loss according to age and total flight time. The following results were obtained : 1) The incidence of noise-induced hearing loss was 36.9% ; The typical C5-dip was 31.2% and high tone loss was 5.7%. 2) The incidence of noise-induced hearing loss was increased with age and the total flight time. 3) The degree of noise-induced hearing loss was not related with age and the total flight time. 4) In the symmetricty of noise-induced hearing loss, symmetrical case rate was 67.3%, that of poorer right was 19.2% and that of poorer left was 13.5%. 5) In subjective symptoms concerning auditory appartus, there were no cases who complained of hearing impairment and dizziness, but tinnitus was complained in 11.5%.