The operative records of 2816 patients undergoing repair for abdominal aortic aneurysm (AAA) from 1955 to 1985 were reviewed. Inflammatory aortic or iliac aneurysms were present in 127 patients (4.5%), 123 men and four women. Most patients were heavy smokers (92.1%). Clinical evidence of peripheral arterial occlusive disease and coronary artery disease was found in 26.6% and 39.4%, respectively. Additional aneurysms occurred in half of the patients; iliac aneurysms were the most common (55 patients), followed by thoracic or thoracoabdominal (17 patients), femoral (16 patients), and popliteal aneurysms (10 patients). Ultrasound and computed tomography suggested the diagnosis in 13.5% and 50%, respectively; angiography was not helpful. Excretory urographic findings of medial ureteral displacement or obstruction suggested the diagnosis in 31.4%. The aneurysm was repaired in 126 patients. Only one patient experienced acute aneurysm rupture, but eight patients had chronic contained leakage. When compared with patients who have ordinary atherosclerotic aneurysms, patients with inflammatory aneurysms are significantly more likely to have an elevated erythrocyte sedimentation rate (ESR, 73% vs. 33%, p less than 0.0001); weight loss (20.5% vs. 10%, p less than 0.05); symptoms (66% vs. 20%, p less than 0.0001); and an increased operative mortality rate (7.9% vs. 2.4%, p less than 0.002). The triad of chronic abdominal pain, weight loss, and elevated ESR in a patient with an abdominal aortic aneurysm is highly suggestive of an inflammatory aneurysm and may be beneficial in the preoperative preparation of the patient for aneurysm repair.