We evaluated the incidence of catheter-related bladder discomfort (CRBD) and the efficacy of solifenacin in preventing CRBD after transurethral resection of a bladder tumor (TUR-BT) in 134 patients with non-muscle invasive bladder cancer. The incidence rate of CRBD at 1 and 2 hours after TUR-BT was 72.2% and 68.1%, respectively. Solifenacin failed to decrease the incidence and severity of CRBD. Background: Catheter-related bladder discomfort (CRBD) secondary to an indwelling urinary catheter is worse after transurethral resection of a bladder tumor (TUR-BT). We evaluated the incidence of CRBD and the efficacy of solifenacin for preventing CRBD after TUR-BT in patients with non-muscle invasive bladder cancer. Patients and Methods: In the present prospective, randomized, multicenter trial, we enrolled 148 patients with non-muscle invasive bladder cancer who underwent elective TUR-BT under general anesthesia. The patients were randomized to group S (n = 72) or group C (n = 76). The primary outcome was evaluable for 134 patients, who were included in the final analysis. Group S received solifenacin (5 mg orally) on the day before, the day, and the day after TUR-BT. The control group (group C) received standard-care. CRBD was assessed at 1 and 2 hours postoperatively. Pain was assessed for 3 days starting 6 hours after TUR-BT using the visual analog scale. Results: The incidence rates of CRBD in groups C and S were 72.2% and 64.5% at 1 hour and 68.1% and 53.2% at 2 hours, respectively. The incidence rates and severity of CRBD at 1 and 2 hours were not different between the 2 groups (P >.05 for both). The visual analog scale scores and the postoperative consumption of analgesics were not different between the 2 groups (P >.05 for both). None of the patients who received solifenacin experienced an adverse event. Conclusion: Pretreatment with solifenacin (5 mg) failed to decrease the incidence and severity of CRBD after TUR-BT.