The pathogenesis of idiopathic retroperitoneal fibrosis (IRPF) has been attributed to an autoimmune response to atherosclerotic lipid material leaking from blood vessels. Corticosteroids and cytotoxic agents have been used for therapy. Based on the immunosuppressive and anti-fibrotic action of mycophenolate, we administered this agent to a patient with biopsy-proven IRPF and achieved a rapid, complete and sustained remission with a 6-year follow-up.