To determine the relationship between comorbidity and outcome after radical cystectomy in Chinese patients by using the Adult Comorbidity Evaluation (ACE)-27 index. Two-hundred-and-forty-six patients treated with radical cystectomy at the Second Xiangya Hospital of Central South University, Hunan Province, China between 2000 and 2010 were retrospectively analyzed. Medical records were reviewed for age, gender, delayed time of radical cystectomy, urinary diversion type, pelvic lymphadenectomy status, TNM stage, and pathological grade. Comorbidity information was assessed by the ACE-27 index. The outcome measurement was overall survival. Univariate and multivariate Cox proportional hazards regression analyses were used to determine the association between comorbidity and outcome. The study population consisted of 215 (87.40%) males and 31 (12.60%) females with a mean age of $62{pm}11$ years. Median duration of follow-up was $47{pm}31$ months. A total of 151 (61.38%) patents died during follow-up. Of those, 118 (47.97%) had at least one comorbidity. According to the ACE-27 scores, 128 (52.03%) patients had no comorbidity, 79 (32.11%) had mild, 33 (13.41%) had moderate, and 6 (2.45%) had severe comorbidities. Multivariate analysis indicated that moderate (p=0.002) and severe (p<0.001) comorbidity was significantly associated with decreased overall survival. In addition, age ${geq}70$ years (p=0.002), delayed time of radical cystectomy >12 weeks (p=0.044), pelvic lymphadenectomy status (p=0.014), and TNM stage >T3 (p<0.001) were determined to be independent risk factors of overall survival. Increasing severity of comorbidity statistically correlated with decreased overall survival after radical cystectomy.