Pulmonary embolism is an unusual complication of Behçet's disease. Our aim study is to analyse epidemiological, physiopathological and evolutive aspects of this condition. Among 153 patients with Behçet's disease according to the criteria of the International Study Group for Behçet's disease, seven (5 men and 2 women mean aged at 26.6 +/- 6 years) were diagnosed as having pulmonary embolism. This was inaugural in 3 cases; for 2 females, pulmonary embolism complicated pregnancy. Cardiac thrombosis was presented in 2 cases and pulmonary aneurysm in 2 patients. Pulmonary infarction has been noted in 4 cases. Protein C, protein S and antithrombin III levels were normal in all cases. One patient was positive for IgG anticardiolipin antibody. The hyperhomocysteinemia has been noted (17 to 30 micromol/) in 5 cases. All our patients were treated successfully by anticoagulation therapy combined with high dose prednisone, colchicine and intravenous cyclophosphamide in 6 patients. Pulmonary embolism is one of the severe and worst prognostic manifestations of the disease. Furthermore, the hyperhomocysteinemia may play an important role in the pathogenesis of such complication. Immunomodulation therapy associated to folate may be beneficial to attenuate this hyperhomocysteinemia especially, when introduced in the early stages.