A 49-year-old woman was found submerged in the bathtub at home. Closed chest compression was performed first by her husband for approximately 10 minutes, and then by ambulance personnel for 37 minutes. She was transported to our hospital's emergency room while cardiopulmonary resuscitation was continued. She received external chest compression for 19 minutes and then open-chest direct cardiac massage for 45 minutes. Major autopsy findings were hemorrhage (approximately 400ml) in the pericardial sac and a large longitudinal 3.5cm laceration of the right ventricle. Histopathological examination of the right ventricle revealed marked fatty infiltrations, which had partially replaced the major cardiac muscle layer. Some of cardiac muscle bundles in the right ventricle were disarrayed with fibrosis and fat. Infiltrations of fat were also seen in the left ventricular wall and septum near the conducting system. These autopsy findings suggest that the major cause of death in this case might have been a lethal arrhythmia due to arrhythmogenic right ventricular cardiomyopathy (ARVC), and that the ruptured right ventricular wall and cardiac tamponade were complications of the vigorous resuscitative efforts. In conclusion, the softened myocardium with massive fatty infiltration in ARVC may be susceptible to CPR-related injuries.