The degree of hearing impairment of chronic otitis media is closely related to the nature of middle ear pathology, especially size of tympanic membrane perforation, conditions of ossicle chain, location of pathologic lesion in the middle ear cavity. Authors studied the relationship between the preoperative hearing acuity and above mentioned middle ear pathology in about 228 ears of chronic otitis media who had had middle ear surgery at Dept. of Otolaryngology, Han Yang University Hospital from 1st, Jan. 1983 to 31th, Jan. 1984. The results were as following : 1) Hearing loss was increased with the increase of duration of the disease. 2) The average hearing threshold of chronic otitis media was bone conduction 14.0dB, air conduction 55.4dB, therefore air-bone gap was 41.4dB. 3) Hearing loss showed increasing trend with the size of tympanic membrane perforation. 4) Hearing loss showed increasing trend in order of normal ossicles without pathologic lesion, normal ossicular chain with pathologic lesion around ossicles, ossicular fixation or ankylosis, ossicular interruption. 5) In the cases of interrupted ossicular chain, hearing loss was greater in the cases of total destruction than in those of partial destruction. 6) In the type of audiogram, ascending and flat type were most frequently observed, showing 47.4%, 39.5%, respectively, especially ascending type was showed very high percentage in the cases of ossicular fixation, 76.9%. 7) Hearing loss in chronic otitis media was more dependent on the state of middle ear pathology than the size of tympanic membrane perforation.