Purpose of the study: The purpose of this study was to describe the data and outcome of OHCA (according to the Utstein style) in Thessaloniki, which is the second largest city in Greece (population approximately: 1,000,000).1National Statistical Service of Greece. De Facto population of Greece [Census 2001]. Athens: 2003. ISSN: 1106-1499.Google Scholar Materials and methods: Emergency medical service (EMS) in Greece is two-tiered and provides basic life support (BLS) by the ambulance crew (which are in most cases the first responders) and advanced life support (ALS) by a mobile intensive care unit (MICU) with a physician on the head of the crew.2Papaspyrou E. Setzis D. Grosomanidis V. Manikis D. Boutlis D. Ressos C. International EMS systems: Greece.Resuscitation. 2004; 63: 255-259Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar The patients of our study were treated over a 5-year period (from January 1, 2000 to December 31, 2004). Automatic external defibrillators (AEDs) were introduced in the standard BLS ambulance equipment after this period. Results: From a total of 1700 cardiac arrests, resuscitation was attempted in 1458 (85.8%) cases, whereas in 242 (14.2%) cases resuscitation was not attempted. Cardiac arrest was witnessed by bystanders in 1470 (86.5%) and by the EMS personnel in 75 (4.4%) cases. Mean EMS arrival time was 8.18 ± 6.8 min for BLS ambulances and 14.59 ± 10.5 min for MICU. Initial rhythm was ventricular fibrillation in 750 (44.1%), ventricular tachycardia in 18 (1.1%), asystole in 858 (50.5%) and other in 74 (4.3%) cases. 596 (40.9%) patients received classical chest compressions, whereas 862 (59.1%) received active compressions decompressions. Return of spontaneous circulation was achieved in 597 (40.9%) patients, whereas in 167 (11.5%) cases, patients were brought to the Emergency Department under cardiopulmonary resuscitation. 149 patients were discharged from hospital (overall survival rate: 10.2%). Conclusion: Our study results that the survival rate after OHCA is relatively poor but in accordance to other similar studies.3Fischer M. Fischer N. Schiittlert J. One-year survival after out-of-hospital cardiac arrest in Bonn city: outcome report according to the 'Utstein style'.Resuscitation. 1997; 33: 233-243Abstract Full Text PDF PubMed Scopus (134) Google Scholar A further study is now conducted concerning data collected after the AEDs introduction in all BLS vehicles.