Lymphomatous involvement of the heart, occurring at initial diagnosis and presentation, is extremely rare. We report here a case of 58 year old man who presented with generalized edema, pericardial effusion, and a large right atrial mass detected by transesophageal echocardiography. There is no other evidence of disseminated lymphoma in this patient. Tumor removal and pulmonary embolectomy was done. Pathologically, the mass was malignant lymphoma, diffuse large cell type. Unfortunately, we have no chance to perform the intensive chemotherapy. The patient discharged in moribund state.