SummaryThe authors describe and comment seven cases of ventricular fibrillation complicating acute myocardial infarction and followed by complete recovery. They insist on the frequency of dangerous arrhythmias appearing early in the course of recent infarction and on the importance of immediate admission in a coronary-care unit of all patients suffering from myocardial infarction. In most cases, the hospitalization can be short, a few days only.The careful observation of the cardiac rhythm and the judicious administration of antiarrhythmic drugs (xylocaïne, ajmaline, procainamide or propranolol) when ventricular ectopic beats appear, should prevent most cases of primary ventricular fibrillation. Should ventricular fibrillation nevertheless occur, electric defibrillation must be immediately accomplished, generally associated with external cardiac massage, artificial ventilation, intensive oxygenotherapy and with an alkaline infusion. After defibrillation, one or more antiarrhythmic drugs will he given at high doses and for several days, to prevent the recurrence of ventricular arrhythmias.