In this article we propose guidelines for rational use of automated external defibrillators and public access defibrillators in the mountains. In cases of ventricular fibrillation and pulseless ventricular tachycardia, early defibrillation is the most effective therapy. Easy access to mountainous areas permits visitation by persons with high risks for sudden cardiac death, and medical trials show the benefit of exercising in moderate altitude. The introduction of public access defibrillators in popular areas in the mountains may lead to a reduction of fatal outcome of cardiac arrest. Public access defibrillators should be placed with priority in popular ski areas, in busy mountain huts and restaurants, at mass-participation events, and in remote but often-visited locations that do not have medical coverage. Automated external defibrillators should be available to first-responder groups and mountain-rescue teams. It is important that people know how to perform cardiopulmonary resuscitation and how to use public access defibrillators and automated external defibrillators.