Computed tomography (CT) has been shown to be useful in evaluation of the intracranial lesion. But now, computed tomography has been appealing as a new radiologic modality applicable to diagnosis and treatment in orthopaedic surgery. The two-dimentional picture, in one tomographic cut of any part under investigation, was able to increase the sensitivity or resolution of detection of lesion and able to overcome the disadvanages of conventional roentgenography. Eighteen patients who injuried pelvic fracture were examined by computed tomography after evaluated by plain radiography and occasionally by standard tomography. In six cases, we get a new additional diagnosis which are not found in conventional radiography. We have found that CT was more sensitive than plain radiography in detecting the sacroiliac joint injury and its around structure injury and hip joint integrity. Of more importance, clinical sign and symptom are valuable in diagnostic process.