The spectrum, pathogenesis, and changing bacteriology of spontaneous abdominal aortic infections is presented. The classic presentation includes fever, positive blood cultures, and a pulsatile abdominal mass. However, most essential in the preoperative diagnosis is having a high index of suspicion. The bacteriologic spectrum is changing, with Salmonella now being the most common organism cultured. Principles of management include aggressive antibiotic therapy, excision of infected tissue, and extra-anatomic bypass. Long-term follow-up for late complications is important. With early recognition and aggressive combined medical and surgical management, increasing numbers of survivors are being reported.