Research suggests that adult children of parents with harmful alcohol use are at increased risk for premature death. This national cohort study investigated mortality in adult children of parents with alcohol use disorder (AUD), adjusting for sociodemographic variables. The study used 1973 to 2018 data from Swedish national registers to compare mortality risk in children who had ≥ 1 parent with AUD (ICD-10 code F10 and its ICD-8 and ICD-9 equivalents) (n = 122,947) and those who did not (n = 2,298,532). A Cox regression model adjusted for year of birth, sex, parental education, and childhood loss of a parent was used. Before the age of 18 years, about 5% of children born in Sweden lived with ≥ 1 parent who had a clinical diagnosis of AUD. Overall mortality was higher in adult children of parents with AUD: hazard ratio (HR) 1.76, 95% confidence interval (CI) 1.71-1.82. Mortality remained elevated after adjustments for sociodemographic factors (HR 1.45, 95% CI 1.40-1.50). Children of parents with AUD had increased mortality from all investigated causes. The highest excess risk was for death from drug-related causes (excluding accidental poisonings) (HR 3.08, 95% CI 2.74-3.46). For most causes, mortality was higher if the mother had AUD than if the father had AUD. Patterns of mortality were similar in both sexes. This study provides evidence that parental AUD raises the risk of offspring mortality from preventable causes such as drug use, suicide (HR 2.16, 95% CI 1.98-2.36), accident (HR 2.00, 95% CI 1.87-2.13), and assault (HR 1.76, 95% CI 1.38-2.24).