Aim: The aim of this study was to analyze possible differences in the use of ambulance service between densely and sparsely populated areas. Methods: This study was designed as a 2-step consecutive study that included the ambulance service in 4 different areas with different geographical characteristics. A specific questionnaire was distributed to the enrolled ambulance services. Completion of one questionnaire was required for each ambulance mission, that is, I per patient, during the study periods. For calculations of P values, geographic area was treated as a 4-graded ordered variable, from the most densely populated to the most sparsely populated (ie, urban-suburban-rural-remote rural area). Statistical tests used were Mann-Whitney U test and Spearman rank statistic, when appropriate. All P values are 2 tailed and considered significant if below .01. Results: The medical status of the patients in the prehospital care situation was more often severe in the sparsely populated areas. In addition, drugs were more often used in the ambulances in these areas. In the sparsely populated areas, ambulance use was more frequently judged as the appropriate mode of transportation compared with the more densely populated areas. Conclusions: Our study suggests that the appropriateness of the use of ambulance is not optimal. Furthermore, our data suggest that geographical factors, that is, population density, is related to inappropriate use. Thus, strategies to improve the appropriateness of ambulance use should probably take geographical aspects into consideration. (C) 2009 Published by Elsevier Inc.