A case of abdominal aortic aneurysm with Bechçet's disease and a review of two similar cases previously reported are presented. This case and additional review of other reported major vascular complications of Behçet's disease lead us to conclude that the pathogenesis of the abdominal aneurysm is related to involvement of the aortic wall or vasa vasorum by the Behçet's disease process. Surgical treatment of this rare complication by Behçet's disease should include extra-anatomic bypass if the possibility of infection cannot be definitely excluded.