This study examines the clinical, hemodynamic, and electrophysiologic findings in a unique group of 11 young (aged 15 months to 29 years) survivors of a cardiac arrest. All patients were previously in good health, and cardiac arrest was the initial manifestation of cardiac disease in all. Overt clinical and hemodynamic abnormalities were not as common as previously reported, and in some instances apparent cardiac abnormalities failed to provide a link to cardiac arrest. No patient had congenital heart disease or hypertrophic cardiomyopathy. However, during multicatheter electrophysiologic study, sustained tachyarrhythmia was reproducibly initiated in 8 of 11 patients (73%). Young, ostensibly healthy patients who survive cardiac arrest form a diverse group. Diligent programmed intracardiac electrical stimulation may demonstrate life-threatening tachycardias in these patients. Treatment to prevent recurrence of cardiac arrest is difficult in this group of patients. However, the ability to initiate tachycardia in the electrophysiologic laboratory may be useful in the management of these patients.