Chronic expanding hematoma(CEH)was first recognized by Reid in 1980. It begins to expand chronically more than 1 month after surgery or trauma, which is considered the possible cause of bleeding. It resembles chronic subdural hematoma. Most of the reports on CEH are those in the thoracic cavity or muscles, and few are in the pericardial cavity after open heart surgery. Our case was a 64-year-old male, who had undergone coronary artery bypass grafting (CABG) 18 years before. He presented with symptoms of heart failure such as exertional dyspnea, general fatigue and appetite loss. Computed tomography( CT) scan showed severe compression of the left ventricle by a large mass, and he was diagnosed with intrapericardial CEH. Resection of the severely calcified epicardium as well as removal of the hematoma in the pericardial cavity was performed, and the symptoms of heart failure improved. No recurrence has been noted for 1 year since the operation. A long-term follow-up will be necessary.