The clinicostatistical analysis of the surgical findings was performed in 451 cases of chronic otitis media, and the results of observation were as follows : 1) The age group of patients who underwent primary ear surgery were mainly in the third and forth decade. 2) The malignant perforation-attic or marginal perforation-was observed more frequently in the cholesteatoma group(48.9%) than the non-cholesteatoma group(6.9%). 3) In the status of middle ear mucosa, the occurrence of granulation tissue was dominant in the cholesteatoma group(68.3%) comparing with the non-cholesteatoma group(26.0%). 4) Tympanosclerosis of the middle ear was found in 14% of total surgery cases. 5) The incus was defected most frequently(46.3%), particularly the defect of the long process of incus was dominant. The hearing loss was greater in the incus-defect cases(average 60.7dB) than the incus-intact cases(average 33.5dB) in both of cholesteatoma and non-cholesteatoma group. 6) The extension of cholesteatoma was the attic-antrum in 32.5%, attic-antrum-tympanum in 26.0%, attic only in 21.9%. 7) The surrounding bony pathologic changes, including exposure of dura mater, facial nerve and the lateral semicircular canal, were shown more frequently in cholesteatoma group(16.9%), than the non-cholesteatoma group(4.4%).