Programmed ventricular stimulation was used effectively in the clinical management of six patients with medically refractory, chronic, recurrent ventricular tachycardia. Critically timed ventricular stimuli reliably terminated episodes of ventricular tachycardia and thus obviated repeated countershocks. Critically timed stimuli also reliably induced reentrant ventricular tachycardia. This provided a "clinical model" allowing immediate determination of optimal suppressive drug regimens. The technique has practical application in selected patients with recurrent ventricular tachycardia and can be safely performed within the intensive-care unit.