Objectives: Emergency medical service systems in Norway are based on equity and equality. A toll free number (113) and criteria based dispatch are crucial components. The establishment of an emergency medical system (EMS) manned by an air and ground emergency physician (EP) has challenged the role of the general practitioner (GP) in emergency medical care. We investigated whether there were any geographical differences in the use of 113, alerts to GPs by the emergency medical dispatch centres (EMDCs), and of the presence of GPs on scene in medical emergencies leading to a turnout of the EP manned EMS. Methods: This was a prospective, observational cohort study of 385 000 inhabitants covered by the two EMDCs of Rogaland county, Norway, including 1035 on scene missions of the EP manned EMS during the period 1998-99. Results: The proportion of emergency calls routed through 113 was significantly lower, the proportion of alerts to GPs significantly higher, and the proportions of GPs on scene significantly higher in rural than urban areas. Conclusion: We found geographical differences in the involvement of GPs in pre-hospital emergency medical situations, probably caused by a specialised emergency medical service system including an EMDC and an air and ground EP manned EMS. There were geographical differences in public use of the toll free 113, and alerts to GPs by the EMDCs, which is likely to result from geographical conditions and proximity to medical resources. Future organisation of the EMS has to reflect this to prevent unplanned and unwanted autonomously emerging EMS systems.