Problems of access to physician services have arisen in Canada at a time when physician hours of work have been undergoing important changes. This study investigates the relationship between physicians' hours of direct patient care and physicians' service supply using individual-level data from a random sample of Ontario general/family physicians. The empirical findings reveal that the variation across physicians in total billing is dominated by the variation in physicians' billings per hour rather than by the variation in physicians' working hours. There is also negative correlation between average billing per hour and average number of hours of patient care. This pattern is shown in analyses of subgroups defined by the gender of the physician, by practice location, by practice type, and by years since graduation.