Peri-aortitis retroperitoneal fibrosis is characterized by a reaction of a variable inflammatory nature while constricting the organs crossing the retroperitoneal space, notably the ureters and the blood vessels. It is difficult to diagnose such a rare disease. We bring about here six cases of periaortic retroperitoneal fibrosis diagnosed from systemic, digestive, urinary or vascular signs. Early diagnosis is often difficult and is shown to be established after an average of three months investigation. The average age of these patients, all of the male sex, is 58 years old (54 to 90). In the six cases this disease appears to be idiopathic even though in two cases it is associated to giant temporal arteritis and polymyalgia rheumatica. TDM remains the best diagnostic tool to point out the existence of this fibrosis, to observe its evolution and to investigate for any extension of the disease. The etiology of this fibrosis remains a mysterious one; however an immunologic origin has been suggested. Medical treatment by corticosteroids is often successful but the long term evolution of the disease is still uncertain.