Retrospective and prospective studies have been undertaken to assess physicians' practice-patterns by studying cardiopulmonary resuscitation (CPR) case summaries. Most summaries reveal similar influences by the physician, patient and situation-related variables on the patterns of resuscitation. The initiation of resuscitation efforts is addressed frequently, but, very few studies discuss the topic of termination of resuscitation. Prehospital emergencies are addressed very rarely. The objective of this study was to introduce a new methodological approach towards initiation and termination of resuscitation efforts in prehospital situations. The subject studied were the physicians' decisions concerning initiation/withholding, termination/withdrawal and the resulting early survival rates. The result is termed the "Resuscitation decision index" (RDI). The "RDI" could be a tool allowing comparisons on a quantitative level, between different EMS systems or disciplines and giving an insight into the decision process. The "RDI" can enhance audit of resuscitation. The process of decision-making can be used to help future theoretical decision-making strategies.