The pathological findings observed following intraoperative radiotherapy (IORT) boost (15Gy) to the whole bladder, external beam fractionated irradiation (46Gy in 5 weeks), and planned radical cystectomy in patients with deep invasive bladder carcinoma are analyzed. Clinical pretreatment stage of disease was T3 (16 cases) and T4 (two cases). No evidence of residual tumor (pT0) was demonstrated in 11 cystectomy specimens (61%) and residual tumor (pT+) was observed in seven (39%). Toxicity and complications related to the treatment approaches were minor and reversible. It is concluded that IORT is a feasible boosting modality in the management of invasive bladder cancer, able to induce high rates of pT0 cystectomy specimens, and might be considered as a valuable technique for organ preservation treatment programs.