Chronic thromboembolic pulmonary embolism not preceded by clinical thromboembolic event(s) in a 50 year-old male with a history of three-year dyspnea on exertion was detected. Proximal chronic pulmonary embolism, mean pulmonary artery pressure 32 mm Hg, and pulmonary vascular resistance of 444 dyn x s(-1) x cm(-5) were found. We describe a 11-year clinical course of anticoagulated patient with monitoring of functional status and echocardiography and with control of pulmonary haemodynamics at the end of follow-up.