BACKGROUND Childhood experiences can influence mental health in adulthood. Parental addiction is a relatively common adverse experience in childhood. However, understanding of the relationship between parental addiction and levels of distress over the adult life course is incomplete. METHODS Data are from the National Population Health Survey longitudinal file (1994/1995 to 2010/2011). Sex-specific trajectories of psychological distress in relation to exposure to parental addiction in childhood were examined among Canadian adults from ages 18 to 74. RESULTS Psychological distress levels decreased with age, but were consistently higher throughout the life course among individuals who experienced parental addiction in childhood, compared with those who did not. The gap in psychological distress scores by parental addiction status was wide in young adulthood, but narrowed as individuals aged. CONCLUSIONS Exposure to parental addiction in childhood can be associated with psychological distress well into adulthood, but levels decrease over time.