A group of 26 patients with pelvic fracture and disruption of the prostatomembranous urethra were evaluated for impotence. Impotence was defined as inability to achieve an erection firm enough for vaginal penetration. Of the patients 25 were potent before the injury, whereas 1 was only 7 years old at injury. Seven patients admitted to being potent after the injury but before the final urethral anastomosis. Four patients became potent after urethroplasty. The definitive operation to the urethra was done approximately 6 months after the injury. Only 11 of the 26 patients (46%) reported erections adequate for vaginal penetration. No patient who had adequate erections before urethroplasty became impotent postoperatively. We believe that the impotence was caused by damage to the neurovascular supply to the penis at injury.