Retroperitoneal fibrosis (RPF), also known as Ormond's disease, is a rare fibroinflammatory disease with uncertain etiology. RPF is characterized by the presence of a particular retroperitoneal fibrotic tissue which is white, woody and involving retroperitoneal structures such as the great vessels, ureters and psoas muscle. The main complication of RPF is the obstruction of local structures such as the ureters due to the fibrosis and the treatment of this aspect represents the main challenge for this pathology. RPF medical treatment consists of corticosteroids or/and immunosuppressive therapy. We report a case of a patient affected by idiopathic RPF treated with low-dose methotrexate (MTX) and 6-methylprednisolone (6-MP) for two years, describing and confirming the effectiveness and safety of a long-term low-dose MTX and 6-MP treatment associated to ureteral Double-J stenting avoiding more invasive surgical approaches.