Primary acquired cholesteatoma is rather frequently encountered with variety of chronic suppurative otitis media in which the perforation is confined within the region of the pars flaccida of the tympanic membrane. It is unpredictable to define the pathologic extension of cholesteatoma into the middle ear cavity and mastoid air cells in spite of the attic perforation. Preoperative knowledge of precisely performed and interpreted high-resolution computed tomography(CT) of the temporal bone may be very helpful to otologic surgeon prior to exploration of attic cholesteatoma. Thirty patients with primary acquired cholesteatoma underwent a computed tomographic examination of the temporal bone prior to surgery and then we compared tomographic findings with operative findings. We analyzed six parameters of the anatomical and pathological features of the temporal bone. In conclusion, the diagnostic accuracy of preoperative CT of the temporal bone in primary acquired cholesteatoma was very high. Therefore preoperative CT of the temporal bone could help otologic surgeons not only to avoid intraoperative complications, but also to decide the appropriate type of surgery and ossiculoplastic materials preoperatively.