In order to evaluate the noisy environment, the status of hearing loss, and risk factors in pilots and ground-workers of ROK air force, noise survey was conducted in 293 worksites of 23 bases from 1993 to 1996 and audiometric tests with 1,868 pilots and 340 ground-workers were carried out from 1994 to 1996. The audiometric test was conducted only air conduction at 500, 1,000, 2,000, 3,000, 4,000 and 6,000 Hz in both ear. The results were summarized as follows : 1. Among 293 worksites in the 23 bases, the noise level of 129 (44%) worksites exceeded 100 dB and their range was 104 ~140 dB. 2. Hearing threshold level was significantly different between age groups at all frequency in both groups of pilots and ground-workers (p<0.05). The older in age, the higher in the level of hearing loss in both ear, especially significant at 4,000 and 6,000 Hz. 3. Among pilots in their thirties, the longer in total flight time, the higher the level of hearing loss at all frequency in both ears except 6,000 Hz in left ear (p<0.05). 4. Among pilots in their thirties, hearing loss of helicopter pilots was larger than the other pilots, showing statistically non-significant difference at all frequency in both ears except 4,000 and 6,000 Hz of left ear. 5. The prevalences of hearing loss over 30 dB at 4,000 Hz in pilots and ground-workers were 6.7% (126/1,868), 28.2% (96/340), respectively. When the subjects were restricted to 40 ~ 49 age group, the prevalences in pilots and ground workers were 10.8% (21/194), 28.0% (70/250), respectively. 6. The prevalences of noise-induced hearing loss in pilots and ground-workers were 0.9% (16/1,868), 3.8% (13/340), respectively. When the subjects were restricted to 30 ~ 39 and 40 ~ 49 age group, the prevalences in pilots and ground workers were 1.2% (10/813), 6.7% (1/15), and 2.1% (4/194), 2.8% (7/250), respectively. In conclusion, the noise level of air base could cause noise-induced hearing loss in some pilots and ground-workers. The risk groups of noise-induced hearing loss in air force are ground-workers and helicopter pilots than the others. Therefore effective noise control and hearing conservation program have to be carried out in risk groups, immediately.