Eleven patients (8 male) with idiopathic retroperitoneal fibrosis (IRPF) were reviewed. The mean age of the patients was 44 years. Five patients (group 1) who had moderate obstruction were treated only by steroids. Six patients (group 2) who presented with severe obstructive uropathy (and/or serious metabolic disturbances) were treated with a combination of surgery and steroid administration. Unilateral or bilateral ureterolysis was performed in 5 patients. It was associated with nephrostomy in 2 cases and intraperitoneal disposition of the ureters in 1 case. Left nephrostomy without ureterolysis was performed in 1 patient. The mean follow-up period was 5.5 years (5 months to 20 years). All patients of group 1 now have normal renal function. In 5 patients of group 2, renal function improved significantly after operation; one of them was started on regular dialysis 16 years later. In another patient, IRPF recurred in the ureter of a living related renal graft 6 months after transplantation. In conclusion, steroid treatment alone offers a long-term survival in patients with IRPF of moderate severity. Combined treatment must be recommended for patients who present with severe obstruction and advanced uremia.