Objectives: To compare comorbidity measures and to analyze survival rates in men undergoing radical prostatectomy at age 70 years or older. Materials and methods: A total of 329 consecutive patients aged 70 or more years who underwent radical prostatectomy between 1992 and 2004 were studied. The patients were stratified by 5 comorbidity classifications, tumor stage, Gleason score, and PSA value. Mortality was subdivided into overall, comorbid, competing, prostate cancer-specific, and second cancer-specific mortality. Competing risk and Kaplan-Meier survival curves as well as Mantel-Haenszel hazard ratios were calculated. Comparisons were made with the log-rank test. Cox proportional hazard models were used to determine the independent significance of prognostic variables. Results: Considering the dose-response relationship, P values and the discrimination of 2 risk groups, the Charlson score was the best of the tested comorbidity classifications in men selected for radical prostatectomy at age 70 years or older. Beside the tumor-related factors Gleason score 8-10 (hazard ratio 2.61, P = 0.0234) and lymph node involvement (hazard ratio 2.89, P = 0.0145), a Charlson score of 1 or greater was identified as an independent predictor of overall mortality (hazard ratio 2.16, P = 0.0441). Without comorbidity or adverse tumor-related risk factors, elderly men had an excellent 10-year overall survival probability (77% to 100%, depending on the classification used), whereas 10-year overall survival was distinctly poor in the presence of lymph node metastases (30%) or Gleason score 8-10 disease (33%). Conclusions: The Charlson comorbidity score may be used to stratify men selected for radical prostatectomy at age 70 years or older and to estimate long-term survival probability. In the absence of adverse tumor-related parameters or serious comorbidity, long-term survival probability is excellent in this subgroup.