Thromboembolic venous disease is both common and potentially serious, thus the first episode of pulmonary embolus calls for careful assessment. This involves two stages: a search for a venous localization of the pulmonary embolus and a search for risk factors contributing to thromboembolic venous disease. The emergence of non-invasive echographic-Doppler techniques and echocardiography make possible the localization of any residual venous thrombus. The risk of post thrombotic disease is raised in symptomatic thrombotic venous disease which requires wearing elastic stockings for a least two years. On the other hand this risk has not been assessed in asymptomatic cases of venous thrombosis. A search for risk factors requires a detailed history, a rigorous clinical examination and a routine list of laboratory investigations. Some complex investigations for detecting the early stages of a neoplasm would not appear justified unless there is objective evidence to support his. At the same time thrombophilia studies are not currently performed routinely for a first episode but may be suggested in the following cases: family history of thromboembolic venous disease, age less than 45, including those in whom the episode occurs at the same time as pregnancy, or whilst taking hormone therapy, idiopathic thromboembolism, the association of arterial and venous thrombi and finally venous thromboses occurring in an unusual anatomical site. Prospective studies have shown the value of long term anticoagulation in patients suffering from constitutional hemostatic anomalies. Finally, if there is an after thought of occult cancer or constitutional thrombocytopenia a careful follow up should be performed particularly during the first year.