A young woman with familial prolongation of the Q-T interval had recurrent convulsive seizures associated with episodes of paroxysmal ventricular fibrillation. Although this potentially fatal disorder is difficult to treat, bretylium tosylate rendered the patient free of symptoms. The recognition of convulsive seizures as the presenting sign in this syndrome is of great importance, for only detailed electrocardiographic study will enable the physician to make the correct diagnosis and search for effective treatment.