We report a case who had myocardial ischemia after release of the aortic cross clamp during mitral valve replacement. Myocardial ischemia was visually estimated by use of intraoperative MCE (myocardial contrast echocardiography). After appropriate treatment the ischemic area disappeared and the patient showed a good postoperative course. MCE is a useful method with which to detect visually the wash out pattern of cardioplegia from myocardium after reperfusion during open heart surgery.