Nine patients with retroperitoneal fibrosis were reviewed. All patients had idiopathic disease, bilateral in eight patients. An IVP on admission was normal in only one of 17 kidneys with delayed excretion in seven. The upper urinary tract was dilated in eight kidneys and no excretion of contrast medium was seen in four; another four kidneys were not examined by IVP because of uremia. Surgical alleviation of ureteric obstruction was carried out by ureterolysis alone (2 ureters), ureterolysis and lateral displacement of the ureter (2 ureters), ureterolysis and neoimplantation into the bladder (2 ureters), ureterolysis and intraperitonealization (2 ureters), and ureterolysis and omental wrap (7 ureters). After surgery, an IVP showed normal excretion in six of the seven kidneys with delayed excretion preoperatively. Two of the four preoperatively nonfunctioning kidneys also showed normal excretion at IVP. Of the four kidneys not preoperatively examined by IVP because of uremia two showed a normal excretion on postoperative IVP. Two ureters developed recurrent obstruction and required additional surgery whereas 10 ureters remained unobstructed in the follow-up period of 26-89 months. Our experience suggests that complete and extensive ureterolysis combined with omental wrapping gives the best results on a long-term basis.