Healthcare staff with the duty to perform CPR should also be capable of using an automated external defibrillator (AED). We investigate whether nurses and physiotherapists can use an AED without prior training. Subjects were tested on a manikin during a cardiac arrest scenario. All 15 untrained subjects could deliver a shock with an AED in 68.8+/-29.2 s (time+/-S.D., range, 40-169 s). Most failed to position the pads correctly (53%) or follow correct safety procedures (67%). After a standardised training session, the time to deliver a shock improved significantly to 48.5+/-5.5 s (range, 41-61 s, P<0.01) and all subjects placed the pads correctly and followed a safe defibrillation procedure. This study shows that nurses and physiotherapists, with no previous AED training, can deliver a shock with an AED. Training improves speed of shock delivery, correct pad placement and safety. This study suggests that it is feasible to train healthcare professionals to use an AED with relatively little training. This should allow rapid deployment of AEDs in those areas of the hospital where cardiac arrests are infrequent and staff do not have rhythm recognition skills.