As part of an ongoing effort to evaluate alternative treatments for benign prostatic hyperplasia, we compared the outcomes of transurethral resection of the prostate with those of open prostatectomy. Men undergoing prostatectomy in Denmark (n = 36,703), Oxfordshire, England (n = 5284), and Manitoba, Canada (n = 12,090), were identified retrospectively through administrative data and followed for up to eight years. The cumulative percentage of patients undergoing a second prostatectomy was substantially higher after transurethral than after open prostatectomy (12.0 vs. 4.5 percent in Denmark, 12.0 vs. 1.8 percent in Oxfordshire, and 15.5 vs. 4.2 percent in Manitoba). The long-term age-specific mortality rates associated with transurethral prostatectomy as compared with open prostatectomy were also elevated in each country. The data on 1650 Canadian patients were used to investigate the contribution of coexisting morbid conditions to the elevated risk of death. The relative risk was 1.45 (95 percent confidence interval, 1.15 to 1.83) before risk adjustment and 1.45 (95 percent confidence interval, 1.15 to 1.84) after adjustment; the higher mortality was seen among low-risk as well as high-risk patients. These findings suggest that transurethral prostatectomy is less effective in overcoming urinary obstruction than the open operation. Our data also raise the possibility that transurethral prostatectomy may result in higher long-term mortality, although we cannot rule out potential confounding effects of unmeasured characteristics of patients.