Introduction: Bystander cardiopulmonary resuscitation (CPR) has been shown to significantly improve outcome in sudden cardiac arrest in children. In view of this, most emergency medicine services deliver telephone instructions for carrying out CPR to laypeople who call the emergency services. Little is known as to whether laypeople carrying out these instructions deliver effective CPR. Methods: Adult volunteers who had no previous experience of CPR were recruited. They were presented with a scenario and asked to perform CPR for 3 min on a training manikin according to the instructions they were given by telephone. Tidal volume, compression rate and depth, time to the beginning of CPR and hand positioning were recorded. Results: Fifty-five volunteers were recruited; three were excluded (two had previous CPR training and one refused to perform CPR). None of the subjects identified correctly that the manikin was not breathing and achieved a level of CPR performance that was consistent with all of the current guidelines. Median tidal volume of rescue breaths was 38mL. Only 23% of subjects delivered rescue breaths of optimal volume (40-50mL) and 23% delivered no effective breaths at all Chest compressions were performed at a median rate of 95 min(-1) with 37% delivering compressions at the optimum rate of 90-110 min(-1). Conclusion: None of our volunteers performed telephone-CPR at a level consistent with current guidelines. Further investigation is necessary to determine whether the instructions can be improved to optimise CPR performance. (c) 2007 Elsevier Ireland Ltd. All rights reserved.