In the resuscitation guidelines revised by the Netherlands Resuscitation Council, the decision has been made to conform with the resuscitation flowchart used elsewhere in the world, and to use the ABC sequence: 'airway-breathing-circulation'. This implies that the CAB sequence ('circulation-airway-breathing'), which has been in use since 1981, has been abandoned. Intrinsic arguments in favour of the CAB scheme are based on animal experiments and observations in humans. They come down to time-saving in the various diagnostic and therapeutic steps, whereby the chance of successful recovery of the circulation increases, and the convalescence phase and the risk of brain damage probably are reduced. In addition, this scheme is better suited to the relatively large group of patients with a cardiac cause underlying their loss of consciousness, and to the preference of lay people to limit themselves to heart massage when attending the patient. Intrinsic arguments in favour of the ABC scheme are not based on scientific data. They concern improvement of the ventilation-perfusion ratio with the first heart massage, oxygenation of the blood in the lung capillaries, improvement of the circulation and the palpability of pulses.