A 51 year old man was admitted to the Thoracic and Cardiovascular Department of Kyungpook University Hospital on April 7, 1976, with chief complaints of orthopnea and the chest pain for about 3 months. Physical examination showed narrow pulse pressure, puffy face, engorged neck veins at sitting position, distant heart sound, enlarged liver and edematous upper extremities. The chest roentgenogram demonstrated markedly enlarged cardiac silhouette. Low voltage and the low to diphagic T`s were noted on the electrocardiogram. Paroxysmal ventricular tachycardia was developed intermittently and was subsided spontaneously. Repeated pericardiocentesis were performed each of which yielded from 100 to 300ml. but intractable cardiac failure was progressed. The bacteriology and cytology of the pericardial fluid were not revealed any specific findings. The pericardiectomy was performed to release the intractable cardiac tamponade. Pericardium was found to be thickened and cardiac constriction was noted. The thickened pericardium was easily removed. A large hen`s egg sized dark blue tumor mass occupied the anterior wall of the right atrium and two thumb tip sized pearl gray tumors were placed at the just below portion of the main pulmonary artery. The biopsy report revealed primary fibrosarcoma of the heart. The patient was improved from the symptoms of the cardiac failure during the postoperative course.[KTCS 1977;1:173-178]