Background/Aims/Objectives: To evaluate the influence of body mass index (BMI) on complications and oncological outcomes in patients undergoing radical cystectomy (RC). Methods: Clinical and histopathological parameters of patients have been prospectively collected within the “PROspective MulticEnTer RadIcal Cystectomy Series 2011”. BMI was categorized as normal weight (<25 kg/m2), overweight (≥25–29.9 kg/m2) and obesity (≥30 kg/m2). The association between BMI and clinical and histopathological endpoints was examined. Ordinal logistic regression models were applied to assess the influence of BMI on complication rate and survival. Results: Data of 671 patients were eligible for final analysis. Of these patients, 26% (n = 175) showed obesity. No significant association of obesity on tumour stage, grade, lymph node metastasis, blood loss, type of urinary diversion and 90-day mortality rate was found. According to the -American Society of Anesthesiologists score, local lymph node (NT) stage and operative case load patients with higher BMI had significantly higher probabilities of severe complications 30 days after RC (p = 0.037). The overall survival rate of obese patients was superior to normal weight patients (p = 0.019). Conclusions: There is no evidence of correlation between obesity and worse oncological outcomes after RC. While obesity should not be a parameter to exclude patients from cystectomy, surgical settings need to be aware of higher short-term complication risks and obese patients should be counselled -accordingly.