Postoperative haemothorax following thoracic surgery is a rare complication, but associated with a high mortality. In the literature, this complication occurs in 0.6 to 4.6% of patients and with a mortality of 5.1 to 17.8%. In minor cases, chest tube placement, application of fresh frozen plasma (FFP) or transfusion can be sufficient to control the situation. In severe cases, re-thoracotomy is mandatory. The most frequent origin of bleeding is a bronchial or intercostal vessel (21 and 16%) or the area of pleural adhesions that were separated (10.5%). The pulmonal artery or vein were the origin of bleeding in 16% of cases while in most cases (37%) active bleeding could no longer be detected. A positive effect on postoperative outcome is observed after an early reoperation.