Computed Tomography and conventional radiography of the traumatic acetabular fractures are analysed in 31 adult patients in whom acetabular fractures were demonstrated or suspected on initial radiographs. The results were as follows: 1. Oblique views are useful in demonstration of acetabular columns and acetabular walls but frequently impossible to perform due to limitation of motion. 2. CT was superior in evaluation of posterior column fracture two column fracture. 3. CT was also superior in demonstration of the acetabular dome posterior column the important components in stability of hip joint. 4. CT reveals hidden loose body soft tissue injury in plain film. 5. Combined reformations of CT was also useful in evaluation of 3-dimensional pathologic anatomy.