15 patients suffering from retroperitoneal fibrosis with ureteral obstruction have been treated. 6 patients were operated at the first onset, 3 after an attempt of corticotherapy and 6 patients had exclusive corticotherapy. Results of surgery referred to kidney units are 9 good results out of 12 and these of corticotherapy 11 good results out of 16. Besides, in the literature, the complications of surgery are frequent and serious. Medical treatment, with renal drainage, when needed is so to consider first, surgical treatment being kept for corticotherapy failure.