Through the pr대perative high-resolution computed tomographic(HRCT) evaluation of the patients with chronic middle ear inflammation, the nature and potential complications of the lesion can be evaluated more accurately than previous imaging modalities. We retrospectively reviewed the HRCT findings of chronic middle ear inflammation in 50 surgically proven cases during recent 2 years. We also compared findings of HRCT and otologic surgery in order to know the diagnostic ability of HRCT about the true nature and extent of soft tissue inflammatory masses within the middle ear and various complications. The results obtained were as follows : 1. HRCT domonstrated the soft tissue inflammatory lesion in the middle ear cavity in all 50 cases. Among theses, 32 cases were confirmed to have cholesteatoma, and 12 cases of granulations tissue including 2 cases of cholestrol granuloma, 3 cases of thickened mucosa and 3 cases of inflammatory exude were verified respectively. 2. Among the 32 ases of cholesteatoma, HRCT showed the ossicular erosion in 87% and other complications in 38% of cases. The types of cholesteatoma can be predicted according to the site and extension of soft tissue mass except in 6 cases. 3. Among the 12 cases of granulation tissue, HRCT also showed the erosion of ossicles in 50% and facial nerve canal in 17%. 4. Pars flaccida type cholesteatomas(21 cases) were most frequently noted in atticoantral area(67%) and pars tensa type(4 cases) in mesotympanum(75%). 5. Incus body and malleus head were the most vulnerable portions of bony erosion in pars flaccida type(10/21). 6. We met some difficulty in differentiation of the soft tissue inflammatory mass in 7 cases. 6 cases of ossicular erosion and 3 cases of other complications were also misinterpreted mainly due to anatomic variations and technical factors of HRCT.