BACKGROUND: Parental absence, due to death or separation from a parent, has been associated with smoking and alcohol consumption in adolescence and adulthood. The aim of this study was to investigate whether parental absence in early childhood was associated with smoking and alcohol uptake before adolescence. METHODS: Data on 10 940 children from the UK's Millennium Cohort Study were used. Logistic regression was used to test associations between parental absence (0-7 years) and reports of smoking and alcohol consumption at age 11. RESULTS: Children who experienced parental absence were more likely to have smoked (OR=2.58, 95% CI 1.88 to 3.56) and consumed alcohol (OR=1.46, 95% CI 1.25 to 1.72). No differences were found by child sex or age, or parent absent. Children who experienced parental death were less likely to have drunk alcohol but those who had were more likely to have consumed enough to feel drunk. CONCLUSIONS: Parental absence was associated with early uptake of risky health behaviours in a large, nationally representative UK cohort. Children who experience parental absence should be supported in early life in order to prevent smoking and alcohol initiation.