CT is a valuable diagnostic modality in evaluation of bladder injury, extension of paravesical hematoma, pelvic bone fracture or injury of adjacent soft tissue although the diagnostic accuracy of bladder injury itself is lower than that of retrograde cystography. We analized CT findings in thirty cases of bladder injury or paravesical hematoma due to blunt lower abdominal or pelvic trauma and compared them with operation fildings in eight cases. IVP in eight cases and cystography in fifteen cases. The types of bladder injury were classified as contusion, intraperitoneal bladder ruptue, extraperitoneal bladder rupture and combined rupture. The locations of paravesical hematoma were classified as perivesical, prevesical or combined. There was no close relationship between the types of pelvic bone fracture and distribution of paravesical hematoma. The paravesical hematomas in fifteen patients without bladder injury were located in prevesical space only. Perivesical hematomas were noted in nine of fifteen patients with bladder injury and were not noted in patients without bladder injury. Thus, we conclud that the presence of perivesical hematoma on CT is a diagnostic sign of bladder injury even though extravasation of contrast from the bladder is not identified, and if there is extraperitoneal hematoma, possibility of bladder injury or other pelvic trauma should be considered.