BACKGROUND To determine optimal management of major abdominal arteriovenous fistulae and define factors affecting outcome. METHODS We reviewed clinical data of 18 patients, 16 males and 2 females, who underwent repair of major abdominal arteriovenous fistulae between 1970 and 1997. RESULTS Sixteen patients had primary fistula, caused by rupture of an atherosclerotic aortic or aortoiliac aneurysm into the inferior vena cava (IVC), iliac, or left renal vein. Two had secondary, iatrogenic arteriovenous fistulae. Seventeen patients (94%) were symptomatic, 11 (62%) had acute presentation. Fistula was diagnosed preoperatively in 8 (44%). Fistula closure (direct suture 16, patch 1, iliac vein ligation 1) was followed by aortoiliac reconstruction in all patients. Caval clip was placed in 3 patients. Early mortality was 6%; 7 patients had major complications. During follow-up (mean 6.1 years) 2 patients died of causes related to fistula closure. CONCLUSIONS Rupture of aortoiliac aneurysms into the iliac veins or IVC carries a better prognosis than intraperitoneal, retroperitoneal, or enteric rupture. Although preoperative diagnosis is ideal, a high index of suspicion, careful repair avoiding pulmonary embolization, and blood salvage were all helpful in keeping morbidity and mortality low. Our data suggest that IVC interruption is seldom warranted.