Sternal injury, gross cardiac pathology and cardiac dysrhythmias following non-penetrating impact by a variety of impactors to the sternum of experimenta animals are described. The biomechanical response of the chest wall to the impact are presented and a correlation between injury severity and chest wall displacement is demonstrated. A simple mathematical model is developed which predicts chest wall displacement when the mass, velocity and dimensions of the impactor are known. The model demonstrates the dependence of chest wall displacement on pre-impact kinetic energy, impactor diameter and target size.