Purpose Photodynamic diagnosis and white-light TURB with adjuvant intravesical chemotherapy (ICT) is widely used in treatment of bladder cancer. This non-inferiority trial is designed to demonstrate non-inferiority regarding recurrence-free survival (RFS) of Hexvix(R) TURB followed by immediate instillation compared to white-light TURB with immediate instillation followed by maintenance ICT. Methods Between 07/2010 and 12/2016, 129 patients with EORTC intermediate risk non-muscle invasive bladder cancer treated with TURB were included in this multicentre phase III study. Patients were randomized and received either white-light TURB with immediate ICT followed by maintenance ICT (n = 62, 20 mg Mitomycin weekly for 6 weeks as induction phase, afterwards 20 mg/month for 6 months) or Hexvix (R) TURB with immediate ICT only (n = 67, 40 mg Mitomycin). Primary study endpoint was RFS after 12 months. Hexvix (R) TURB was counted as non-inferior to white light alone if the upper limit of the one-sided 95% confidence interval of hazard ratio was lower than 1.676. Due to the non-inferiority design, the per-protocol population was used as the primary analysis population (n = 113) Results Median follow-up was 1.81 years. Hexvix (R) group showed more events (recurrence or death) than white-light group (19 vs. 10) resulting in a HR of 1.29 (upper limit of one-sided 95%-CI = 2.45; p(non-inferiority) = 0.249). The ITT population yielded similar results (HR = 1.67); 3.18], p(non-inferiority) = 0.493). There was no significant difference in overall survival between both groups (p = 0.257). Conclusion Non-inferiority of Hexvix (R) TURB relative to white-light TURB with maintenance Mitomycin instillation in intermediate risk urothelial carcinoma of the bladder was not proven. Hence a higher effect of maintenance ICT is to assume compared to a Hexvix (R)-improved TURB only, confirming its important role in patient treatment.