Sex differences in absence from work were investigated for parents and nonparents during a period of 11 months. Personnel records showed sex differences only among working parents, with mothers taking significantly more sick leave than fathers (p < .05). By using self-reports obtained under protection of anonymity it was found that in the parent group both sexes reported absences necessitated by child care as personal illness, but significantly more women than men were absent from work for such activities (p < .01). Results from this study shed light on the statement that “women are more likely than men to be absent from work because of illness” (U.S. Department of Labor Bureau Bulletin, 1977); child care, rather than personal illness, appears to be the major variable that mediates sex differences in absence from work.