The authors, who have successfully performed thrombectomy of the pulmonary artery under extracorporeal circulation and deep hypothermia in three patients, wish to draw attention to the principal factors of success. The decision to operate, as accepted by most surgeons, rests on the patient's functional status (stage III or IV) and on the presence of a systolic pulmonary arterial pressure exceeding 50 mmHg. Deep hypothermia combined with circulatory arrest seems to be the best method, as it improves visual control, thereby avoiding damage to the endothelium or fracture of the distal thrombi during thrombectomy. Finally, a new approach route (severing of the superior pulmonary vein, opening of the pulmonary artery and use of Volmar-Sisteron strippers) makes it possible to remove the entire thrombus, thus obtaining an almost normal pressure in the pulmonary artery. In all three patients, the complications that are mostly due to intrabronchial haemorrhage by disruption of the endothelium, fracture of the distal thrombus or pulmonary artery contusion were avoided.