Chronic periaortitis (CP) includes idiopathic retroperitoneal fibrosis, inflammatory abdominal aortic aneurysms and perianeurysmal retroperitoneal fibrosis. These entities are characterised by a fibro-inflammatory tissue which develops around the abdominal aorta and the iliac arteries, and spreads into the surrounding retroperitoneum to entrap adjacent structures such as the ureters. CP often affects patients with advanced atherosclerosis, and several lines of evidence support the view that it could result from a local inflammatory reaction to antigens in the atherosclerotic plaques of the abdominal aorta such as oxidised-low density lipoproteins and ceroid. However, because most CP patients also suffer from constitutional symptoms and show elevated acute-phase reactant levels, positive autoantibodies and, in some cases, autoimmune diseases affecting other organs, CP may also be considered a manifestation of a systemic autoimmune disease. CP is usually diagnosed using computed tomography or magnetic resonance imaging, but retroperitoneal biopsy may also be necessary; positron emission tomography is useful in assessing the full extent of the disease and the metabolic activity of the retroperitoneal tissue. Ureterolysis and aneurysm repair are frequently performed, but the inflammatory and chronic-relapsing nature of the disease often compels the use of medical therapy, which is based on steroids and immunosuppressants.