A family with the Romano-Ward syndrome is described. A 28-year-old woman had episodes of syncope due to self-terminating ventricular tachycardia torsades de pointes. During lidocaine treatment she developed a sustained ventricular tachycardia and cardiopulmonary resuscitation was necessary. Propranolol reduced ventricular ectopic activity, but the QTc interval remained prolonged. A "threshold" in QT duration for the generation of complex ventricular arrhythmias was observed in the patient. There were no late ventricular potentials noted in the signal averaged ECG in the patient and in members of her family.