A sixty-year-old man presented to an emergency room with rapidly progressing shortness of breath and chest discomfort in April 2013. Echocardiography revealed cardiac tamponade with a large amount of pericardial effusion and a mass in right atrium. Four hundred and twenty mL of bloody fluid was drained by pericardiocentesis. Laboratory analysis of the pericardial effusion failed because of the high viscosity. The patient was referred to our institution. Cardiac magnetic resonance imaging (MRI) revealed a 4.5 × 3.5 cm sized infiltrative mass in the right atrium. In 18F-Fludeoxyglucose-positron emission tomography (FDG-PET) scan, the cardiac mass showed high FDG-uptake without any evidence of distant metastasis. Surgical resection of cardiac tumor was performed, in which the pericardium was thickened without adhesion, and a blackish friable protruding mass was observed within the right atrium near the inferior vena cava. The pathology diagnosis was angiosarcoma. There was no gross residual disease on surgical field and on postoperative cardiac MRI, although microscopic examination showed tumor involvement of the resection margin. The patient was treated with adjuvant concurrent chemoradiotherapy (CRT) 5000 cGys/30 fractions with five cycles of weekly docetaxel (25 mg/m2). He tolerated the treatment very well except for several episodes of palpitation, which started after surgery and before initiation of CRT. Paroxysmal atrial fibrillation was diagnosed that subsided after completion of CRT. There was no evidence of recurrence until April 2014, when three liver metastases were found on liver MRI. The patient was treated with hepatic metastasectomy and palliative chemotherapy with weekly paclitaxel for 16 weeks until when new liver metastases were noted in January 2015. Then he subsequently received pazopanib for another 6 months. He eventually died of disease progression in October 2015; overall survival was 32 months.