Left atrial myxoma constitutes the most significant cardiac tumors, which occupies 30 to 50% of the total in most pathological series with the age range from 3 to 83 years, mostly between the age of 30 to 60 years. Over 90% of myxomas occur in the atria, with 3 to 4 times as many occurring in the left as in the right. They may cause severe and progressive disease mimicking mitral valvular disease with non-specific general symptoms. Recent attentions were focussed in the clinical features along with various diagnostic techniques including angiocardiography, echocardiography and cross-sectional sector scanning echocardiography, and definitive treatment with surgical removal under direct vision using cardiopulmonary bypass. There are several reports on the atrial myxomas removed from various cardiac chambers in Korea, and we report another typical case of left atrial myxoma of 6.8 x 3.8 x 1.7 cm3 attached to the upper margin of fossa ovalis with a short pedicle, also with calcification at it`s distal free end. 29 year old young mother complaining of mild fever, vaginal spotting, numbness of left upper and lower extremities, nocturnal attack of dyspnea and palpitation for 2 months was diagnosed as large left atrial myxoma with the aid of angiocardiography and echocardiography. Trans-right-atrial, transseptal surgical removal of the tumor was successfully performed under the cardiopulmonary bypass for 22 minutes on 24th of July 1980. Postoperative hospital course was uneventful and discharged from hospital on the 12th POD with complete recover from the previous symptoms and signs.