The primary cardiac tumor was considered as a form of disease with poor prognosis in the past and it was hardly diagnosed before post mortem autopsy. But recent development of diagnostic procedure and the cardiac surgery using extracorporeal circulation increased the accuracy of diagnosis and the opportunity of successful treatment. The authors present two cases of left atrial myxoma which experienced during recent 4 years between 1979 and 1982. A 33 year old woman admitted with severe shortness of breath, generalized edema, ascites and the evidence of hepatopathy resulted from right sided heart failure. Preoperatively, the patient was treated with conservative medication to improve general condition for a few days. The tumor mass was removed successfully under the cardiopulmonary bypass. She, however, died of myocardial dysfunction showing low blood pressure. The tumor mass weighed 22gm and measured 5.2x4.5x3.6 cm in size. A 60 year old man admitted with shortness of breath on exertion and an episode of fainting. Following the removal of tumor mass under the cardiovascular bypass, the clinical course was satisfactory with no complication. The tumor mass weighed 105gm and measured 9x4x5 cm in size. [KTCS 1982;4:402-408]