With the increasing participation of women in the physician workforce, it is important to understand the sources of differences between male and female physicians' market labour supply for developing effective human resource policies in the health care sector. Gendered associations between family status and physician labour supply are explored in the Canadian labour market, where physicians are paid according to a common fee schedule and have substantial discretion in setting their hours of work. Canadian 1991, 1996, 2001 and 2006 twenty percent census files with 22,407 physician observations are used for the analysis. Although both male and female physicians have statistically indistinguishable hours of market work when never married and without children, married male physicians have higher market hours, and their hours are unchanged or increased with parenthood. In contrast, female physicians have lower market hours when married, and much lower hours when a parent. Little change over time in these patterns is observed for males, but for females two offsetting trends are observed: the magnitude of the marriage-hours effect declined, whereas that for motherhood increased. Preferences and/or social norms induce substantially different labour market outcomes. In terms of work at home, the presence of children is associated with higher hours for male physicians, but for females the hours increase is at least twice as large. A male physician's spouse is much less likely to be employed, and if employed, has lower market hours in the presence of children. In contrast, a female physician's spouse is more likely to be employed if there are three or more children. Both male and female physicians have lower hours of work when married to another physician. Overall, there is no gender difference in physician market labour supply after controlling for family status and demographics.