Primary cardiac epithelioid hemangioendothelioma (EHE) is extremely uncommon. To our knowledge, only fourteen cases have been reported. We report a case of a primary EHE of the right atrium which incidentally detected in 77-year-old woman. Echocardiograhpy revealed a 26 × 16 mm right atrial mass attached to the base of the interatrial septum and moderate regurgitation of the tricuspid valve. The tumor and stalk were completely resected from the interatrial septum with a partial resection of the septal leaflet of the tricuspid valve. The patient had an uneventful postoperative course and no signs of recurrence nor metastasis of EHE 4 years after operation. Because of malignant potential of EHE, a longer period of close follow up is necessary.