Like presbycusis the, noise induced hearing loss(NIHL) cannot be undone, but unlike presbycusis, it can be prevented or at least minimized with reasonable precautions and protections against noise exposure are taken. The noise induced hearing loss appears in various patterns on pure tone audiogram(PTA). In diagnosis of NIHL, therefore, it is important to estimate not only the patterns of hearing loss on PTA but also past history of exposure to noise. We performed audiologic evaluation for 226 selected patients in 381 retired coal miners. The following results were obtained : 1) The mean working duration was 17 years and average hearing loss was 43dB. 2) There was a significant difference in hearing loss between the group of less than 5 years and the groups of more than 5 years in duration. 3) There was no significant difference in hearing loss according to initial age. 4) The most common type of audiogram was type II(abrupt drop). 5) Patterns of hearing loss showed shifting from type I to type III or IV according to the increase of working duration.