The surgical treatment of cardiac myxosarcoma is reviewed with emphasis placed on palliative response to radiation therapy. A case of primary myxosarcoma of the left atrium in a 16 yr old girl is presented. The tumor was surgically removed in October, 1967. Recurrently myxosarcoma was removed in August, 1968, at which time involvement of the pulmonary veins and the pericardium was noted. Subsequent to postoperative radiation therapy, the patient remained symptom free for more than 3 yr. Death occurred 4 1/2 yr after the original operation from local and systemic recurrence of the tumor.