A 68-year-old female has developed dyspnea on effort for 5 years. On admission, a grade 2/6 apical systolic regurgitant murmur was noted. Chest X-ray examination showed moderate cardiac enlargement. Echocardiogram showed a highly echoic mass with acoustic shadow in the left atrium which was attached to the interatrial septum. A partial herniation of the tumor through the mitral annulus in diastolic phase and moderate mitral regurgitation was noted. Ultra fast computed tomography of the chest revealed a left atrial mass with high density area. At operation the mass was excised with atrial septum through the right atriotomy. Microscopic findings showed the myxoma with bone and bone marrow formation.