A 27 year old woman presented with recurrent episodes of disabling paroxysmal sinus tachycardia (150 to 180 beats/min) in the absence of identifiable organic disease. Tachycardia was resistant to all drug therapy. Programmed stimulation could not induce the tachycardia but high dose propranolol therapy failed to suppress sinus tachycardia in response to isoproterenol infusion. Because of the disability resulting from refractory tachycardia, the patient underwent a new operative procedure to create exit block around the region of abnormal impulse formation. This resulted in the appearance of a stable junctional escape rhythm at 60 beats/min. No adverse effects occurred and the patient has remained free of symptoms after a follow-up period of 10 months.