Gastrointestinal bleeding secondary to spontaneous rupture of an infected abdominal aortic aneurysm into the duodenum is a rare and highly lethal clinical occurrence, representing roughly a third of all primary aortoduodenal fistulas. Diagnosis is problematic due to the subtleties in the clinical presentation and course, and surgical treatment is usually delayed, representing a challenge even for the experienced vascular surgeon. The overall mortality is over 30% and the operative approaches are still controversial. Two cases of ruptured infrarenal aortic aneurysms complicated with aortoduodenal fistula were recently treated at our institution. Bacterial aortitis was documented by arterial wall cultures positive for Klebsiella and Salmonella species respectively. The clinical courses and outcomes of the two patients (one survivor ) treated with retroperitoneal debridement and extra-anatomic bypass and a review of the modern surgical treatment are herein described.