Previous studies have found that female dentists work fewer hours per year than male dentists. This study examined factors which may explain the differences in hours worked per year that exist between male and female dentists in private practice. In 1988, a weighted, stratified random sample of dentists in Australia was surveyed by mailed questionnaire. There were 855 respondents (response rate = 75.5%) with 566 dentists from private practice (361 males and 205 females). Annual time devoted to dental practice was significantly lower for females, for dentists who were not the sole earner of the family income, and for dentists with young children. A significant interaction between sex of dentist and child age showed that hours per year in practice decreased only for females with young children. Hours worked per year were significantly higher among female dentists with no children, or older children. For males, hours worked remained at a higher level. The amount of time devoted to dentistry requires monitoring in the estimation and projection of capacity to supply dental services.