This paper explores the relationships among physician supply, workload (output per physician), and utilization (physician services per capita) in rural Manitoba. Surgery taking place within a patient's home area and that taking place outside this area are discussed. Longitudinal and cross-sectional analyses are compared. Although the average surgeon does more surgical procedures than does the average general practitioner, the number of procedures performed varies greatly within each specialty. Individual physician workloads remained fairly stable over time when a surgically active physician moved into an area, while population utilization increased 17 per cent. When such physicians left an area, the surgical workloads of the physicians increased significantly (18.7 per cent) while population utilization stayed essentially the same. Both physician workload and surgical utilization in control areas increased gradually (between 6 and 7 per cent) over the period studied. Several models of physician behavior were investigated using data on individual procedures as well as overall figures. A model emphasizing the importance of physician discretion appeared to provide the best fit with the data.