Recurrent, medically refractory ventricular tachycardia is usually associated with ventricular aneurysms after myocardial infarction, but aneurysmectomy alone has not been consistently effective in abolishing this dangerous arrhythmia. Therefore, we have used endocardial and epicardial mapping during induced ventricular tachycardia in 30 consecutive patients to identify the probable site where arrhythmia originated in the endocardial tissue. Complete resection of the site was possible in 27 patients, and partial resection in three. In addition aneurysmectomy was performed in 27 patients, and coronary-bypass grafting in 21. There were two operative and three late nonarrhythmic deaths. None of the 25 surviving patients have had ventricular tachycardia during follow-up of four to 28 months; three patients, who had incomplete resections, have required antiarrhythmic drugs. We conclude that surgical therapy of recurrent ventricular tachycardia can be improved through identification of the endocardial origin of the arrhythmia followed by appropriately guided resection.