Otosclerosis occurs when the normal ivory-like endochondral bone of the otic capsule is replaced by foci of spongy vascular irregular new bone. Eventually these foci of haversian bone become more solid. There anr two typesof otosclerosis : fenestral and retrofenestral or cochlear. The cochlear type is much less common and rarely occurs without fenestral involvement. Otosclerosis occurs very rarely in blacks and orientals ; in otolaryngologic articles in Korea there are few reports of otosclerosis, and then only the fenestral type. This is a case reportof cochlear otosclerosis that can be diagnosed on temporal bone CT.