Background: Substantial variation in survival following out-of-hospital cardiac arrest (OHCA) is described both internationally and nationally. The Utstein factors account for half of the variation, but the remaining is not fully understood. Local regulations or guidelines concerning the withholding and termination of resuscitation may influence the reporting of cardiac arrests when comparing outcomes between different Emergency Medical Service systems. Method:We have developed an online cross-sectional mixed-methods explanatory design survey aimed at describing the international and national variations in the initiation, the termination of resuscitation, and the refraining from resuscitation of adult patients (>18 years of age) suffering from non-traumatic OHCA. The respondents will be national experts and the questionnaire will be distributed among members of European Prehospital Research Alliance, the International Liaison Committee of Resuscitation, the European Resuscitation Council, and the Resuscitation Academy.Each invited country will have to identify at least two national experts with special expertise in prehospital resuscitation practices. We exclude countries with less than two respondents.Results: The survey will provide both quantitative and qualitative data. Quantitative data will be presented as frequencies and proportions. Qualitative data will be analyzed using content analysis. Conclusion:This survey could be of importance in understanding the multiple factors leading to the substantial variation in survival found following OHCA. Furthermore, the interpretation of future studies on OHCA from different settings may be improved to further increase survival following OHCA.