The clinical value of CT in the diagnosis of pelvic bone fractures is being explored. Conventional radiographic projections, including internal and external oblique views, although very helpful, often cannot provide sufficent jnformation to give a true sense of the fractures. CT conversely displays the anatomy in an axial plane, thereby providing the missing pieces of information and fascilitating classification of these fractures. From January 1983 to June 1986, 34 patients with pelvic bone fractures, admitted to Department of Orthopedic Surgery, Severance Hospital, were given both CT and conventional radiographs. Comparing the conventional radiographic findings with those of CT, the following conclusions were obtained. 1. For patients with multiple trauma who necessitate position changes during conventional radiography, no further change in position was required during CT. 2. CT clearly showed intraarticular loose bodies, anterior wall fractures of the acetabulum, and separations of the saicroiliac joint which were hardly detected on conventional radiographs. 3. CT permitted a better evaluation of the shape, extent, and degree of separation of fracture fragment, so it was very helpful in formulating the treatment plan. 4. Follow-up CT was helpful in evaluating the effectiveness of treatment.