A 71-year-old man who had been on peritoneal dialysis for 6 years was referred to our hospital for renal transplantation from a living donor. Preoperative echocardiography revealed diffuse severe hypokinesis, a left ventricular ejection fraction (LVEF) of 25%, and a pedicled floating mass in the right atrium. He had not exhibited positive symptoms of active endocarditis or metastatic malignant tumor, and the causes of cardiomyopathy seemed to be uremic and/or ischemic factors. Renal transplantation was postponed, and the extirpation of the mass in the right atrium was scheduled. LVEF improved to 48% 2 months following the induction of hemodialysis before the cardiac operation. Pathohistological findings of the extirpated intra-atrial mass showed sphachelus and fibrotic thrombus, which meant asymptomatic healed infective endocarditis. He recovered uneventfully, and underwent a living renal transplantation from living donor 5 months after the cardiac operation. LVEF further improved better to 56%, and his performance status was remarkably improved. These results imply that renal transplantation and hemodialysis in peritoneal dialysis patients with uremic cardiomyopathy can achive improvement of cardiac function and enable a safe cardiac operation.