Because computerized tomography is often the first test performed in patients with blunt abdominal and pelvic trauma we designed a prospective study to determine if it might be as accurate as retrograde cystography in the diagnosis of bladder rupture. Patients who had suffered blunt trauma with gross hematuria or who had pelvic fractures and microhematuria underwent computerized tomography followed by retrograde cystography. A urethral catheter was inserted and clamped during computerized tomography to ensure bladder filling. Of our first 2 patients computerized tomography showed no evidence of opacified urinary extravasation in 1 and only subtle evidence in the other. Cystography revealed gross intraperitoneal extravasation of opacified urine in both patients. Presently, retrograde cystography, including a film of the distended bladder and a drainage film, remains the most reliable test in suspected bladder rupture.