Programmed electrical stimulation (PES) of the heart has been used to initiate and terminate ventricular tachyarrhythmias under controlled conditions in patients in whom these arrhythmias have occurred spontaneously. The long-term reproducibility of the response to programmed cardiac stimulation in patients with ventricular arrhythmias is unknown. Seventeen patients with previously documented spontaneously occurring ventricular tachyarrhythmias were evaluated: 5 with nonsustained ventricular tachycardia (VT), 10 with sustained VT and 2 with ventricular fibrillation. The underlying cardiac diagnosis was atherosclerotic coronary heart disease (CAD) in 11 patients, dilated cardiomyopathy in 2 patients, congenital heart disease in 1 patient and no structural heart disease in 3. All patients underwent PES in the absence of antiarrhythmic drug treatment, and patients with inducible VT underwent serial electrophysiologic-pharmacologic testing in an attempt to suppress the arrhythmia. All 17 patients were reexamined with PES at a mean of 18 months (range 2 to 42) after their initial electrophysiologic study, during which time none had a myocardial infarction or intervening cardiac surgery. Repeat electrophysiologic studies, performed in the absence of antiarrhythmic agents, were undertaken because of drug intolerance, availability of new drugs, recurrent arrhythmia or preoperative reevaluation. All 11 patients with CAD had inducible VT on both the first and second electrophysiologic evaluation. Of the 6 patients with no CAD, only 1 had inducible VT on both occasions. Thus, long-term reproducibility of PES-induced VT in patients with stable CAD appears to be high.