Current Advanced Cardiac Life Support (ACLS) guidelines and emergency medical services (EMS) clinical protocols usually recommend immediate defibrillation for victims of out-of-hospital cardiac arrest who have ventricular fibrillation (VF). However, animal studies and results from a small number of clinical investigations now suggest that a short period of chest compressions or ACLS procedures delivered before defibrillation may improve the outcome of patients with prolonged VF. Although the basic science and clinical data supporting a chest-compression-first procedure are compelling, large, multicenter randomized trials are still necessary to determine whether such protocols do indeed improve outcome. In current EMS dispatch practice, traditional cardiopulmonary resuscitation (CPR) instructions are given when needed to bystanders who report a possible cardiac arrest. Recent literature has shown that in certain circumstances, CPR instructions involving chest compressions alone may be given more quickly and can yield an equivalent, if not better, chance of survival. Although this practice is controversial, the general consensus is that any CPR is better than none at all. Therefore, telephone CPR protocols that recommend the immediate initiation of chest compressions may be preferred, particularly for callers who have no previous training in CPR.