Prior to establishing a protocol for pre-arrival instructions for cardio-pulmonary resuscitation in the Vienna emergency medical system dispatch centre, a study was performed to determine whether any problems exist which may compromise guidance for basic life-support on the telephone. To evaluate the feasibility of prearrival instructions, a retrospective analysis of cardiac arrest calls was performed. We reviewed the Vienna emergency medical services dispatch centre tape recordings, ambulance run sheets and the hospital charts of 114 patients suffering from atraumatic cardiac arrest. Analysis showed that in 59 cases the arrest occurred in the victim's home. The telephone and the patient were either in the same or in adjoining rooms in 55% of the calls. We did not experience any technical or language difficulties. The caller and victim were related in 51 cases. The callers were completely calm in 77% and fairly calm in an additional 15%. Not one caller was distraught. Our data show that most objections to the feasibility of pre-arrival instructions can be refuted. We conclude that in Vienna the setting and location of arrest will impose few problems on the performance of bystander-cardio-pulmonary resuscitation using pre-arrival instructions given by dispatchers.