The aetiology of chronic thromboembolic pulmonary hypertension (CTEPH) is not clearly understood. In some patients, the disease is preceded by acute pulmonary embolism (APE), and is characterised by intravascular thrombosis, vasoconstriction, inflammation and remodelling of pulmonary arteries. Ensuing pulmonary hypertension leads to potentially fatal chronic right ventricle failure. Both inborn and acquired risk factors were identified. Pathogenesis of haemostatic disorders is not completely explained, and extrinsic coagulation pathway disorders may play a role in CTEPH aetiology.