BACKGROUND/AIM: [corrected] Idiopathic retroperitoneal fibrosis (IRF) is an uncommon disease characterized by a retroperitoneal fibrotic tissue that often involve the ureters, leading to the obstructive nephropathy and variable impairment of renal function. Findings strongly suggest an autoimmune etiology. Surgery, medical treatment with immunosuppressive drugs, or a combination of both are proposed. The optimal treatment has not been established yet. The aim of this study was to present our experience with combined immunosuppressive therapy of IRF, steroids (S) and mycophenolate mofetil (MMF). METHODS: We prospectively followed four patients with IRF from January 2004 to December 2006. Three patients had an active disease with bilateral hydronephrosis. In the two of them acute renal failure was presented, and ureteral catheters were inserted in one in order to manage ureteral obstruction. One patient has came to our unit with a relapse of IRF and incipient chronic renal failure after the prior therapy with ureterolysis and immunosuppressive drugs (azathioprine and tamoxifen). All patients received steroids and MMF. Two patients were treated with intravenous methylprednisolone pulses (250 mg each), for three consecutive days, followed by oral prednisone 0.5 mg/kg/day. The other two patients received oral prednisone at the same dose. Prednisone was gradually tappered to a maintenance dose of 10 mg/kg/day. Simultaneously, all patients received MMF, initially 1 g/day with the increase to 2 g/day. RESULTS: After four weeks of the therapy all symptoms disappeared, as well as a hydronephrosis with a decrease of erythrocyte sedimentation rate and Creactive protein (CRP) to normal level in all patients. Three patents remain in remission untill the end of the follow up. One patient had a relapse because of stopping taking the therapy after six months. He was treated by oral prednisone 0.5 mg/kg/day, which was gradually decreased. After twelve weeks hydronephrosis disappeared and CRP returns to the normal level. CONCLUSION: The combination of steroids and mycophenolate mofetil led to the remission of IRF with a strong and quick immunosuppressive effect. It also provided avoiding the long-term use of high steroid dose and surgical procedures.