Ventricular fibrillation (VF) is a frequently reported terminal cardiac electrical activity in adults. Such data are unavailable for pediatric patients. Terminal cardiac electrical activity determined in 100 pediatric patients was bradycardic arrest throughout the death process in 88% of newborns, 67% of infants, and 64% of children. Although bradycardic arrest was more common, the incidence of ventricular tachyarrhythmias was higher in patients who had congenital heart disease, who had received cardiopulmonary resuscitation, who were beyond the neonatal period, and/or who weighed greater than 2.23 kg. No definite associations could be established between arterial blood gases, electrolyte values, and type of terminal cardiac electrical activity. The development of VF may be related to cardiac mass and the developing autonomic nervous system and therefore is less likely to occur in patients with a small heart.