The authors report their experience with US and CT in 31 cases of inflammatory aneurysms out of a study population of 200 patients with abdominal aortic aneurysms. The work started with a case that had not been diagnosed at US, either due to the operator's poor knowledge of this pathologic condition or because of improper examination technique. The authors stress the importance of a high-frequency probe and proper gain settings which are often necessary for a good visualization of the anterior aortic wall. The correct diagnosis of the inflammatory nature of the aneurysm has been assessed by US ever since, in all cases except for very obese and meteoric patients. In our series, US diagnostic accuracy was 78%, versus 33% reported in literature. US was not accurate in evaluating adjacent structures involvement within fibrous tissues (ureteral narrowing, caval narrowing)--which CT did. Neither US nor CT exhibited reliable diagnostic accuracy in demonstrating enteric involvement within fibrous tissues.