A 32-year-old female patient presented with dyspnea and palpitation, and transthoracic echocardiography revealed the presence of pericardial effusion. Pericardiosynthesis was performed for drainage. Because of the rapid accumulation of effusion and the presence of a right atrial mass on follow-up echocardiography, a computed tomography scan was done that revealed a right atrial defect and the presence of advanced pericardial effusion. The patient was prepared for an emergency operation. The mass on the right atrial wall was approached via a midsternal incision with cardiopulmonary bypass. The tumor filled the right atrial cavity, compressed vital structures, extended to the right ventricle, and had local metastases. As the tumor did not appear to be curable with surgery, a palliative approach was adopted. The right atrial free wall and tissues causing cardiac obstruction were totally removed, the tumor itself was partially excised, and local metastases were sampled. The resulting right atrial wall defect was closed with a Dacron patch. The operation ended uneventfully, and the clinical status and vital and hemodynamic findings of the patient returned to normal. The pathological diagnosis based on the samples obtained during the operation was angiosarcoma. The patient had an uneventful postoperative period and was then referred to an oncology center for clinical recovery. No findings of local recurrence or metastases were observed during the postoperative follow-up. The patient completed her combination therapy and currently is free of any clinical problems at her 13th postoperative month. We believe that advancements in radiotherapy and chemotherapy regimes combined with surgery (radical, if possible) for the treatment of cardiac angiosarcomas may provide better survival and quality-of-life results.