This study aimed to assess whether children's age at their parents' divorce is associated with depression in early and mid-adulthood, as indicated by medication purchase. A sibling comparison method was used to control for unobserved factors shared between siblings. The data were extracted from the Norwegian Population Register and Norwegian Prescription Database and included about 181,000 individuals aged 20-44 who had experienced parental divorce and 636,000 who had not. Controlling for age in 2004, sex, and birth order, children who were aged 15-19 when their parents divorced were 12 per cent less likely to purchase antidepressants as adults in 2004-08 than those experiencing the divorce aged 0-4. The corresponding reduction for those aged 20+ at the time of divorce was 19 per cent. However, the association between age at parental divorce and antidepressant purchases was only evident among women and those whose mothers had low education.