A primary cardiac malignancy is a very rare diagnosis. The most prevalent malignant cardiac tumors are angiosarcomas. Autopsy specimens, microscopic slides, clinical and intraoperative data from a 72-year-old woman referred to our hospital with a suspected mediastinal tumor were studied. The patient was diagnosed with primary cardiac angiosarcoma by microscopic examination under surgery and underwent resection of the tumor, which compressed and obstructed the right atrium and ventricle. She was discharged from our hospital after 3 weeks and died of right heart failure 2 months after the operation.