The effect of empiric antiarrhythmic therapy with quinidine and procainamide on long-term mortality was examined in 209 patients with coronary artery disease resuscitated after out-of-hospital cardiac arrest. The antiarrhythmic agent used was determined by the patient's private physician without knowledge of the study ambulatory electrocardiogram. Of the 209 patients, procainamide was prescribed in 45 (22%), quinidine in 48 (23%) and no antiarrhythmic therapy in 116 (55%). Digoxin therapy was initiated in 101 patients. The 2-year total survival rate for the quinidine, procainamide and nontreated patients was 61, 57 and 71% (p less than 0.05), and for sudden death was 69, 69 and 89% (p less than 0.01), respectively. These observations suggest that empiric antiarrhythmic therapy in survivors of out-of-hospital cardiac arrest did not affect total mortality and was associated with an increased frequency of sudden death.