Behçet's disease is an uncommon systemic process generally developing during the third or fourth decade of life. Recurrent inflammatory lesions are characteristic. Cardiovascular involvement, which may be arterial or venous, is rare but with particularly severe prognosis. Four cases of abdominal aortic aneurysm are reported. One patient underwent emergency surgery for acute rupture. All patients were male, age range 29-45 years, mean age 36.5 years. Three patients were followed for Behçet's disease. Surgical revascularization was performed in all four patients, mainly with prosthetic grafts, one with patch aortoplasty. The postoperative period was complicated by paraplegia and thrombosis of the prosthetic graft in the patient who underwent emergency surgery. On the basis of these cases and cases reported in the literature, it can be concluded that morbidity and mortality are high because of the etiology underlying vascular involvement in Behçet's disease.