Delayed unilateral pulmonary embolectomy via the peripheral approach has been performed in 12 patients suffering from chronic pulmonary vascular obstruction after a single or repeated embolisms. Arterial hypoxemia and pulmonary hypertension were present in all cases. Embolectomy was performed several months or years after the initial event. There were 2 early and one late death. The surviving patients are doing well clinically and show definite hemodynamic and angiographic improvement.