The prevalence of different CPR techniques and the use of adjuncts during the resuscitation attempt by the members of the emergency medical service (EMS) system [bystander, emergency medical technician (EMT), ward nurse, tiered nurse or paramedic, mobile intensive care unit (MICU) has been registrated prospectively during a 5-year period by 7 major Belgian EMS systems. A total of 4548 cardiac arrests have been registered, 3083 happened outside and 1465 inside the hospital. Evaluation of the methods used for assessment of quality of the CPR techniques revealed that this approach was biased both by the status of the health care provider and by the outcome of the patient. Nevertheless, it was evident that the well-accepted standards and guidelines for CPR and emergency cardiac care (American Heart Association and Safar) are poorly applied. This seems to be influenced by the qualification, the experience and the training level of the health care provider. In 998 of 3053 studies out-of-hospital arrests (33%) CPR was initiated by bystanders. Of these, 59% were bystanding health care workers. They performed external chest compression (ECC) more frequently than mouth-to-mouth insufflation (MOMO) (poor technique: 16-19%). In 18% the rescuers were family members who applied more MOMO than ECC (poor technique: +/- 50%). Laymen (23%) performed more ECC than MOMO (poor technique: +/- 33%). EMT and ward nurses apply mainly the bag-valve-mask technique. The bag-valve-tube technique is more frequently used by nurses of a tiered system. The MICU-team applies usually the bag-valve-mask prior to intubation.