Abstract Background: Local control of MIBC by bladder-sparing approach is unsatisfactory. In order to improve the effectiveness of radiotherapy, we have designed a protocol that combines TURB with a non-conventionally fractionated radiotherapy “concomitant boost. Aim of Study: To evaluate the response rate and toxicity criteria in patients with transitional cell bladder cancer treated with maximum Transurethral Resection (TUR), followed by 3-D conformal radiotherapy with a concomitant boost and weekly cisplatin with shortening of overall treatment time. Patients and Methods: Between July 2017 to June 2018, 20 patients with a T2-T3 N0M0 transitional cell carcinoma of the bladder underwent transurethral resection of bladder tumor as much as safely possible (maximum TURBT). They received radiotherapy delivered in short overall treatment time with a concomitant boost technique. With this technique, a dose of 40Gy in 2-Gy fractions was administered to the small pelvis with a concomitant boost limited to the bladder tumor area plus a margin of 15Gy in fractions of 0.75Gy. The total tumor dose was 55Gy in 20 fractions in 4 weeks. Weekly Cisplatin (30mg/m2) was administered weekly concurrently with radiotherapy. Cisplatin was interrupted in case of hema-tological or renal toxicity. The National Cancer Institute Common Toxicity Criteria, version 5, scale was used to assess the chemotherapy and acute radiation toxicity {Common Terminology Criteria for Adverse Events (CTCAE), Version 5.0, November 2017}. We assessed late toxicity using The Radiation Therapy Oncology Group/The European Organiza-tion for Research and Treatment of Cancer (RTOG/EORTC) Late Radiation Morbidity Scoring Scheme. Results: The feasibility of the treatment was good. Severe acute toxicity >!G3 was observed in two patients (10%). Severe late toxicity >!G3 was observed in one patient (5%). Fourteen patients (70%) showed a complete and three (15 %) a partial remission after treatment. Conclusion: In external radiotherapy for muscle-invasive bladder cancer a concomitant boost technique coupling a partial bladder boost with shortening of the overall treatment time provides a high probability of local control with acceptable toxicity.