Background: Muscle-invasive bladder cancer (MIBC) is managed with radical cystectomy or (chemo)radiotherapy ((C)RT), CRT offers the chance of cure alongside organ preservation. Patients presenting with MIBC are often elderly and frail, with comorbidities precluding cystectomy and systemic treatment. We report outcome data for our institution of patients treated with radical (C)RT. Methods: Patients with T2-4N0 MIBC diagnosed between December 2014 and December 2021 were retrospectively identified from the radiotherapy planning system. Baseline demographic, clinical and follow up data were collated from electronic patient records. Results: 54 patients were identified. Mean patient age was 78.5 (range 47 – 94); 51 patients had urothelial cancer and 3 squamous cell carcinoma. 20 patients had evidence of carcinoma in situ (CIS) at diagnosis. 19 patients had neoadjuvant chemotherapy (NACT) (13 patients had cisplatin-gemcitabine, 6 patients had carboplatin-gemcitabine). 12/19 patients completed 3 cycles of NACT, 7 patients received 1-2 cycles. 24/54 patients had concurrent chemotherapy (6 patients receiving mitomycin-5-FU, 17 weekly gemcitabine and 1 weekly cisplatin). 14/24 patients completed concurrent chemotherapy as planned. Of the 24 patients treated with CRT, 18 had NACT. 12 patients received 64 Gy 32 fractions, 2 received 60 Gy 30 fractions, and 40 received 55 Gy 20 fractions. All except 1 patient completed the prescribed course. With a median follow up of 9.4 months (range 0.7-79 months), 3-year overall survival was 43% for all patients; 63% with CRT and 21% with RT alone (log-rank test p=0.0052 HR 3.15 (95% CI 1.48-6.7)). At 3 years 49% were free of recurrence (distant or local); 72% with CRT and 25% with RT alone (log-rank test 0.0079 HR 3.12 (95% CI 1.38-7.01)). 3yr OS and % free of recurrence were not impacted by the presence of CIS. OS was 46% with CIS and 41% without (log-rank test p=0.6649); 3yr % free of recurrence was 43% with CIS and 49% without (log-rank test p=0.4055). Median time to recurrence with CIS was shorter at 13.3 months vs 26.1 months. Conclusions: Radical radiotherapy to the bladder is an effective option for the treatment of MIBC and should be routinely discussed with patients. Patients should be treated with CRT as opposed to RT alone as both OS and RFS are significantly improved. Ensuring patients are fit to receive systemic treatment alongside RT may require prehabilitation in this elderly and more co-morbid group.