The vascular involvement of Behçet's disease is nowadays considered as an important sign of the clinical evolution of these patients. It can affect both the arterial and the venous territories. Superficial thrombophlebitis is the most common vascular manifestation. Thrombosis of deep veins is relatively rare and it generally appears within the inferior vena cava territory as a late manifestation in the evolution of the disease. We describe two cases of Behçet's disease which presented, at an early stage, thrombosis of the superior vena cava as the more relevant manifestation of the disease. The evolution of both patients was satisfactory with the combination of cyclophosphamide and colchicine. The etiopathogenesis of this manifestation and its therapeutic possibilities are discussed.