This paper describes the ways in which encounter data from the family practice teaching units of the Department of Family Medicine, University of Western Ontario, have been used for teaching, service, and research. The fact that family physicians may deal with several problems at one visit is emphasized, as is the need to report morbidity in terms of the population at risk, so that comparisons can be made with other work. The value of encounter data in studies of patient utilization and resident experience is noted. The validity of the data has been examined and the extent of underrecording assessed. The system has helped to encourage the spirit of inquiry in its users.