Idiopathic retroperitoneal fibrosis is a rare disorder of an unknown etiology characterized by an inflammatory proliferative fibrosing process that may involve the ureters in 80-100% of cases.  The present study was carried on a 38 years old man who was admitted to Imam Khomeini Hospital with severe abdominal pain and renal failure. Abdominal MRI showed encasement of abdominal aorta and bilateral hydroureteronephrosis. Tissue biopsy established the diagnosis of retroperitoneal fibrosis and ureteral obstruction was managed by insertion of bilateral ureteral stents. Presupposing the un-resectability, medical therapy was started. However he didn’t show objective response to Prednisolone (1mg/kg) and had adverse effects. Subsequently, his disease was controlled by adding mycophenolate mofetil and azathioprine to reduce the steroid dose. After a few months, urinary stents were removed and he had been on complete remission for more than 4 years. Although advanced idiopathic retroperitoneal fibrosis would be effectively treated by a combination of ureteric stents and steroids, in difficult cases, second-line treatment with other immunosuppressive drugs may help to achieve long-term remission of disease.