This study was undertaken to determine the frequency and type of continuing education required in areas with various populations and evaluate the resuscitation knowledge and skills possessed by Standard First Aid Class (SFAC) ambulance crews, who play a major role as prehospital care providers in Japan. Two hundred SFAC ambulance crews were classified into four subgroups based on the population of the areas they serve a population greater than 400 000, 150 000–400 000, 50 000–150 000 and less than 50 000. A survey regarding continuing education in each area revealed that the EMS systems with smaller populations had less adequate continuing education than in larger populated areas. A written test consisted of 80 multiple choice questions showed no difference among each population subgroup. In the five-point skills test, however, it was demonstrated that the resuscitation skills, particularly those required for the airway management, of SFAC ambulance crews in the areas populated by less than 50 000 had deteriorated more than those in larger communities. These findings re-emphasized the importance of adequate continuing education in low-volume, part-time, rural EMS systems where lack of clinical exposure is a significant limiting factor for skill retention.