Blunt chest trauma in pediatric patients can result in various injuries to the myocardium. Cardiac concussion (commotio cordis) is seen in patients in whom the precordium has been struck with relatively little force at a vulnerable period of the cardiac cycle. These patients have no predisposing cardiac problems, and autopsy reveals no evidence of heart damage. The usual clinical presentation is that of immediate collapse secondary to a lethal arrhythmia. Prevention is the cornerstone of potentially decreasing the incidence with the aid of safety equipment and, possibly, immediate defibrillation.