Retroperitoneal fibrosis (RPF) is a rare fibro-inflammatory condition that is idiopathic in most cases, but may be secondary to various causes. Although the cause and pathogenesis of the idiopathic form are unknown, immunogenetic factors and immunopathologic/autoimmune mechanisms are probably involved. Idiopathic RPF usually develops around the abdominal aorta and iliac arteries but in some cases may also involve the thoracic aorta and the origin of its major branches, with a pattern similar to that of other forms of large-vessel vasculitis. In addition, the disease is frequently associated with autoimmune conditions affecting other organs. Glucocorticoids alone or in combination with immunosuppressive agents are usually effective treatment options, but the disease frequently has a chronic relapsing course.