We aimed to investigate the influence of preoperative factors on postoperative renal function and the association between renal function and oncologic outcomes and complications after radical cystectomy (RC). Materials and Methods: We retrospectively analyzed patients who underwent RC due to muscle-invasive bladder cancer and intravesical treatmentresistant nonmuscle-invasive bladder cancer in our center between January 2006 and March 2017. The patients' age, gender, comorbidities, preoperative estimated glomerular filtration rate (eGFR), presence of hydronephrosis, hydronephrosis grade and laterality, urinary diversion type, preoperative and postoperative pathology findings, eGFR at postoperative 3 rd month, oncologic outcomes, and complication rates were evaluated. The patients were divided into 2 groups based on postoperative eGFR: group 1 (<60 mL/min eGFR) and group 2 (≥60 mL/min eGFR), and data were compared between the groups. Results: The study included 125 patients with urothelial carcinoma of the bladder who underwent RC and had complete records (59 patients in group 1 and 66 patients in group 2). Of the preoperative factors, only presence of hydronephrosis was significantly higher in group 1 (p=0.012). There were no statistically significant differences between the groups in terms of urinary diversion type, pathology findings, oncologic outcomes, or complications. Conclusion: Preoperative eGFR and hydronephrosis were significantly associated with postoperative 3 rd month eGFR. Postoperative eGFR <60 mL/min was not associated with diversion type, pathologic and oncologic outcomes, or complications.