In cardiac arrest the interval between the collapse and defibrillation may be shortened by teaching lay people to use defibrillators. We conducted a 3-year prospective, community-based study on public access defibrillation (PAD) in an urban emergency medical services system. All public sites with a cardiac arrest incidence of at least one per year were equipped with automated external defibrillators. Twenty cardiac arrest patients were enrolled, seven in PAD and 13 in control group. Defibrillation was accomplished significantly earlier (P = 0.01) in the PAD group. The direct costs were 110 270 Eur and only 13.5-16% of this figure would be related to the cost of defibrillators during their 8 years lifespan. This study showed that a community based model of PAD shortens the time to CPR and defibrillation significantly in an urban environment but various challenges have to be solved before wider implementation of PAD. In future projects the nature of the costs especially should be considered. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.