Although noise-induced hearing loss (NIHL) is the most prevalent occupational disease in Korea, only 10% of the diagnosed cases are compensated. Old (1989-94) and current diagnostic criteria, criteria for workers' compensation of NIHL in Korea, compensation formulas of American Medical Association/American association of Ophthalmology and Otolaryngology (AMA/AAOO), the Committee on Hearing, Bio-Acoustics, Biomechanics (CHABA), American Academy of Otolaryngology (AAO) recommendation were compared. Each criterion was applied on the audiomety data of 4044 workers (8023 ears), who had received the second line screening test of Special Periodic Health Examination Program for noise-exposed workers during 1991-2. First, the resulting proportions of NIHL cases by employing each criterion were compared and strength of agreement was measured using kappa value. Temporary Threshold Shift (TTS) was corrected by noise free interval, and the reduction ratio of NIHL cases was calculated. Theoretical progression model of NIHL was reconstructed from previous studies on the natural course of NIHL to evaluate the change of diagnosis result of each criterion in the model. The kappa value between old and current criteria was 0.19, 0.55 for current criteria and workers' corn. criteria, ranging from 0.08 to 0.78, highest coincidence was observed between current criteria and CHABA formula. The current criteria produce most similar results with CHABA formula. If TTS is corrected for NFI, there is about 14 % reduction of NIHL cases. The results of applying on NIHL progression model divided the formulas roughly into 3 groups, of which compensation criteria was the most, old criteria and AAO the least conservative. In conclusion. The result of 4 KHZ audiometry should be excluded in evaluation of hearing level and a new hearing conservation program should be set out. Current diagnostic criteria has an ambiguity in that managerial concept for prevention arid! purpose of compensation is mixed up. The current diagnostic criteria and compensation criteria could be incorporated'into 'a new formula which is based on the state of the art test for estimating everyday hearing disability.