Recent advances in otologic surgical techniques, involving the use of an operation microscope, have led toincreased demands inaccurate radiological diagnosis of the temporal bone. However, the difficulties of roentgendiagnosis of cholesteatoma of hte middle ear are frequently experienced. Authors reviewed a total of 248 cases ofmastoid roentgenograms (165 cases of cholesteatoma and 83 cases of chronic otitis media without cholesteatoma)surgically proven at Seoul National University Hospital from March 1977 to June 1980 in order that diagnosticvalue of routine mastoid roentgenogram(Towne and Law views) could be determined. The results are as follows; 1.Detection rate of cholesteatoma is 68.5% with Towne view only and 62.4% with Law view only, while both Towne andLaw veiws, it is increased up to 73.9%. 2. False positive is 10.8% even with both Towne and Law views. 3. A newsimple technique, transorbital magnification view, is introduced to visualize the detailed anatomic structures ofthe ear.