Arrhythmias occur as a life-threatening complication in adults with severe head injuries. A wide spectrum of brady- and tachyarrhythmias and different pathogenetic mechanisms have been described. We report an 8-year-old boy with traumatic brain injury who developed a variety of independent types of arrhythmias during the course of his illness, including supraventricular and ventricular extrasystoles, prolonged QT duration and ventricular fibrillation, accelerated junctional rhythm, and reentry tachycardia. Each arrhythmia may have had a distinct pathogenic pathway, and not all were associated with raised intracranial pressure.