The nature and severity of injury and biologic characteristics of the injured (e.g. age, physical condition) are principal factors in establishing the demands made upon the operation of emergency medical service systems with respect to the timeliness and adequacy of emergency care. Some data on fatal and non-fatal motor vehicle traffic injuries, the response to notification of the occurrence of injury, and the condition of injured are presented. Survival potential and necessary conditions for survival of the DOA cases are analyzed;​ three case histories are given. Precise data from different urban and rural areas are needed to permit generalization of findings. The medical community can contribute injury data;​ precise information on time of the accident is essential and must be provided by other sources.