[en] Clinical effects of radiation on bladder are in relation with their effects on various tissues of this organ. The most important is the vessels. According to clinical models; it is possible to evaluate the different factors, especially the dose and the irradiated volume. The risk of complications rise with these two factors. Drugs used in bladder cancer don't seem to increase the risk of complications. The prevention of the late effects lies on the tissue protection and on the precise evaluation of the irradiated volume in view to reduce them. (author)