Chronic thromboembolic pulmonary hypertension (CTEPH) is an uncommon disease with a severe prognosis. Initially considered as a constantly fatal disease, it can be cured since the advent in the late 80's of thromboendarterectomy. CTEPH occurs in approximately 0.1% of patients who survive acute pulmonary embolism. Such outcome is due to the failure of the normal thrombi resolution in the pulmonary circulation. This disease is observed in both sexes and occasionally as early as in the third decade. Many patients have no history of acute venous thromboembolism which is responsible for the frequent diagnosis delay. Therefore, it is of paramount importance to search for pulmonary vascular disease when patients complain solely of dyspnea on exertion. These patients should undergo echocardiography and, if necessary, right heart catheterization. Once the diagnosis of pulmonary hypertension is established the next step is to find the cause. Ventilation-perfusion scanning is probably the most sensitive non-invasive test to provide evidence that pulmonary hypertension is related to chronic thromboembolism. Angiography and helical computed tomography allow to confirm the diagnosis of CTEPH and to determine whether it is accessible or not to thromboendarterectomy. Most patients who undergo thromboendarterectomy improve clinically and in terms of gas exchange and pulmonary hemodynamics. When thrombi are inaccessible surgically, patients should be placed on the list for lung transplantation if they fulfill the criteria established for primary pulmonary hypertension. When all surgical procedures are contraindicated, anticoagulant and oxygen therapy remain the sole possibility of treatment.