A 52-years-old female patient was admitted with an invasive anterior mediastinal mass. Frozen section analysis of the mediastinotomy revealed lymphoma. In the morning of the first day following surgery, sudden onset of massive hemorrhage induced by cough was present from the chest drain. The patient was immediately taken to the operating room and a median sternotomy was performed subsequently. Massive hemorrhage arising from another site of the biopsy site was detected. Anterior mediastinal mass was resected completely and superior vena cava reconstruction with polytetrafluoroethylene graft was performed. The patient was discharged on ninth day following surgery. We presented this case due to the rarity of this complication.