Most sudden cardiac deaths in man are associated with events causing myocardial ischemia and only 40-60% of these patients are successfully resuscitated. Further progress in reducing the mortality from such events will depend on a better understanding of the interventions used during CPR. Animal models currently used for the study of CPR do not involve myocardial ischemia. A new model of cardiac arrest (spontaneous ischemic ventricular fibrillation) in closed-chest dogs resembles more closely the events occurring in man. Initial controlled, randomized studies of the model demonstrate that it responds to resuscitation in a manner similar to human resuscitation. Further study of this model during CPR may lead to changes in patient care which will improve survival from episodes of sudden cardiac death.