Retroperitoneal fibrosis or Morbus Ormond is a rare disease characterized by inflammatory fibrosis of the retroperitoneal space and the abdominal aorta often including the common iliac arteries. The abdominal aorta can be enlarged leading to a classification of retroperitoneal fibrosis with or without aneurysm of the abdominal aorta. The classic form of retroperitoneal fibrosis usually presents without aneurysm of the abdominal aorta. Clinical presentation is not specific and includes abdominal, flank or back pain. Mechanisms, initiating factors and pathophysiology of the disease have remained unclear to date, however there is evidence that autoimmune mechanisms are involved. The most relevant complication of retroperitoneal fibrosis is the involvement of the ureter leading to obstructive nephropathy and requiring relief from obstruction. Because of the low frequency of the disease associated with a great variety of presentation no randomized controlled trials are available. Drug therapy is limited to steroids alone or in combination with immunosuppressive drugs such as azathioprine or even cyclophosphamide. The response to medical therapy is variable from patient to patient. Clinical endpoints are general symptoms, sedimentation rate, and imaging studies with abdomen CT or MRI.