To compare different comorbidity classifications as predictors of survival after radical prostatectomy (RPE). 444 consecutive RPE patients (mean follow-up 6.9 years) were stratified according to age, Charlson score, American Society of Anesthesiologists Physical Status classification (ASA), New York Heart Association classification of cardiac insufficiency, classification of angina pectoris of the Canadian Cardiovascular Society and a combination of both cardiac risk scores. Comorbid and overall mortality were the study endpoints. Mantel-Haenszel hazard ratios, p values and 8-year survival probabilities were used for comparison. A modified Charlson score was created by a restriction to the five individual conditions significantly associated with comorbid mortality. When three strata (low, intermediate, high risk) were used, all stratifications displayed dose-response patterns and reached statistical significance as predictors of survival at least for the high-risk group. Only the ASA classification, however, discriminated three significantly different risk groups. Only the modified (restricted) Charlson score reached statistical significance as predictor of comorbid mortality in the age group of 70 or more years. Although all investigated comorbidity classifications had some prognostic relevance in patients selected for RPE, their clinical applicability appears to be limited beyond the 70th year of life. The results of this study might, nevertheless, assist the treatment decision in patients with low-risk tumors eligible for modern watchful waiting strategies who mainly belong to the age group between 60-69 years where comorbidity seems to be of distinct prognostic value.