OBJECTIVE: Based on the natural history of localized prostate cancer, the life expectancy (LE) of men treated with either radical prostatectomy (RP) or definitive external-beam radiotherapy (EBRT) should exceed 10 years. To test this hypothesis, we examined overall survival rates after RP or EBRT in a contemporary population-based cohort. METHODS: Within a population-based cohort we assessed crude survival in 17 570 men diagnosed with prostate cancer who were either treated with RP (n = 9678) or definitive EBRT (n = 7892) between 1989 and 2000. Age and Charlson Comorbidity Index (CCI) score at treatment represented covariates. In order to control for prostate cancer-related mortality, we repeated analyses for 9131 men who did not receive any secondary treatment for prostate cancer. RESULTS: In the entire cohort, the actuarial 10-year survival probability after RP was 75.3%, versus 36.7% after EBRT (p <0.001). In those who did not receive any secondary treatment, the actuarial 10-year survival probability after RP was 81.1%, versus 30.4% after EBRT (p <0.001). In multivariate Cox regression models, EBRT was associated with a 2.8-fold (p <0.001) and 3.9-fold (p <0.001) higher risk of mortality in the entire cohort and in the cohort without secondary treatment, respectively. Increased CCI score and increased age were also associated with a higher risk of mortality (p <0.001). CONCLUSION: Some men treated with EBRT and, to a lesser extent, those treated with RP may have insufficient LE to warrant therapy with curative intent. More stringent selection criteria are necessary to avoid overtreatment.