A total of 103 patients with pelvic fracture due to blunt trauma were evaluated by cystography and 10 cases of bladder rupture were identified. Risk factors associated with the likelihood of bladder rupture included gross hematuria, the number of fractured pubic rami, tachycardia, hypotension, and declining hematocrit. We conclude that since 90 percent of the patients do not have bladder rupture when a pelvic fracture is encountered, cystography may be safely reserved for those patients with pelvic fracture who are considered to be at high risk for such an injury.