We report the case of a young man with severe pulmonary hypertension caused by multiple thromboembolism subsequent to congenital protein C deficit. During the previous phase to haematological treatment we showed a very poor response to vasodilators evaluated by Doppler-Echocardiography. The etiological diagnosis was confirmed and initialized the anticoagulant treatment. We had observed a significant regression of peak gradient atrioventricular by continuous wave Doppler and a complete clinical normalization.