Infected aortic aneurysms are uncommon but important because they can lead to uncontrolled sepsis and/or aortic rupture. Symptoms are frequently minimal during the early stages and a high index of suspicion is essential to make the diagnosis. The surgical literature suggests that survival is markedly improved by a prompt diagnosis and aggressive surgical intervention. Our recent experience with 5 cases who underwent arteriography and/or computed tomography (CT) prior to surgery was reviewed and these diagnostic methods compared. Traditionally, arteriography has been considered indispensable in the evaluation of infected aortic aneurysms but the aneurysm lumen must reach a certain size before it can be detected and, even then, the extraluminal component may be underestimated. CT, with contrast enhancement, was more sensitive in the early stages of the disease and provided a more complete depiction of the anatomic abnormalities. Mural enhancement preceded the increase in the aortic lumen with disruption of aortic wall calcification. An earlier and more accurate diagnosis can be provided by CT than by angiography without the disadvantages of its invasiveness and cost.