Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by obstruction of the large pulmonary arteries by acute and recurrent pulmonary emboli with subsequent organization of these blood clots. Because of a lack of clinically evident acute-pulmonary embolism episodes in >50% of patients, the diagnosis of CTEPH can be difficult. Lung ventilation/perfusion scintigraphy showing segmentary mismatched perfusion defects is the best diagnostic tool to detect CTEPH. Although pulmonary endarterectomy is considered the treatment of choice for patients with CTEPH, it can not be performed in a substantial proportion of patients. Medical therapies have been increasingly used in subcategories of CTEPH patients.