Radiation cystitis is a lesion of the bladder caused by irradiation of a pelvic organ. These lesions can range from a simple inflammatory reaction to almost complete bladder retraction. The frequency of chronic lesions is estimated to be between 5% and 10% of patients receiving pelvic radiotherapy. Radiation cystitis generally presents in the form of macroscopic haematuria associated with frequency and urgency. The diagnosis is often easy due to the patient's history of pelvic irradiation. Cystoscopy demonstrates a pale, frosted bladder mucosa with scattered telangiectasias and sometimes well defined torpid ulcerations. The treatment of radiation cystitis is essentially symptomatic, mainly consisting of controlling the episodes of haematuria by bladder lavage. Several more or less specific treatments have been proposed in order to decrease the episodes of haematuria. The treatments most frequently used are intravesical instillations of formalin, silver nitrate or alum with an efficacy on symptoms of about 70%. Another more recent and very encouraging treatment option is hyperbaric oxygen therapy, which allows better tissue diffusion of oxygen, improving neo-angiogenesis by increasing the vascular density of irradiated tissues. This technique is effective in about 80% to 90% of cases with a lasting effect. It also allows objective improvement of the bladder mucosa. Finally, in severe cases of persistent haematuria, arterial embolization or even cystectomy with urinary diversion may be proposed.