Objective: Chronic otitis media is the infection of the middle ear and mastoid air cells. Cholesteatoma is keratinized squamous epithelium formation in the middle ear. Although the two diseases may be recognized with clinical examination, sometimes it may not be possible. While treatment of chronic otitis media includes antibiotic therapy or surgery, cholesteatoma is treated surgically. In this study, we aimed whether quantitative measurement of the soft tissue density in the middle ear on temporal bone CT may be used as a criterion for discrimination of chronic otitis media and cholesteatoma.