In two instances patients with previous symptoms of myocardial infarction collapsed suddenly and became pulseless. Artificial respiration was given by insufflation, and immediate thoracotomy was performed to permit rhythmical manual compression of the heart, which was in a state of asystole. Intracardiac injection of 0.5 cc. of 1:1,0001,000 aqueous solution of epinephrine was followed by ventricular fibrillation. Normal cardiac rhythm was restored by use of an electrical defibrillator in each case, and both patients survived without signs of injury to the brain. This is in accord with other published data indicating that these methods of resuscitation, if applied without delay, greatly improve the prognosis of patients with acute myocardial infarction.