Twenty-one patients with bacterial aortitis were treated in four institutions over a 10-year period. Clues to the diagnosis were a pulsatile mass; fever; positive blood culture; CT scan revealing aortic nodularity, an aneurysm of irregular configuration, or air in the aortic wall; and angiography revealing a lobulated aneurysm. The most commonly identified organisms were Salmonella and Staphylococcus. Excision with in situ repair was performed in nine patients; 11 patients underwent extraanatomic bypass grafting with aortic ligation. In situ graft repair was performed when the infected aorta could be removed entirely or when the thoracic or suprarenal aorta was involved. Axillofemoral bypass grafting was used when infection was extensive. There were eight disease-related deaths. No graft infections were encountered in patients who survived.