Thrombo-endarterectomy for chronic thromboembolism of the pulmonary artery can be recommended in patients with NYHA classification III or IV symptoms, mean pulmonary artery pressure greater than 30 mmHg and proximal, greater than 50% obstruction of the pulmonary arterial bed. Pulmonary angiography for localization of thrombi is prerequisite. Surgical techniques encompass lateral thoracotomy with or without extracorporeal circulation and median sternotomy with extracorporeal circulation. As an adjunctive measure, an interruptive procedure for the vena cava is performed. Currently we prefer to operate with the beating heart and normothermia. The most frequent complications are congestive heart failure and hemorrhagic pulmonary edema. In 33 patients total mortality was 20%. On use of a median sternotomy, with normothermia and beating heart there were no deaths. In the presence of distally-localized obstruction, thrombectomy cannot be performed.