In this case report two patients, having severe intra-abdominal injuries after cardiopulmonary resuscitation (CPR) with the LUCAS system, are presented. They both underwent surgical intervention. Severe intra-abdominal injuries following manual CPR are rare, but little is known about the incidence of these injuries associated with mechanical CPR. We have reviewed the literature on clinical outcome and adverse events after out-of-hospital cardiac arrest with LUCAS CPR and manual CPR, and our conclusion is, that more research is needed to establish the safety of mechanical chest compression systems.