Background Few population based studies have investigated associations between parental history of alcoholism and the risk of alcoholism in offspring. The aim was to investigate in a large cohort the risk of Alcohol Use Disorders (AUD) in the offspring of parents with or without AUD and with or without hospitalisation for other psychiatric disorder (OPD). Methods Longitudinal birth cohort study of 7177 men and women born in Copenhagen between October 1959 and December 1961. Cases of AUD were identified in three Danish health registers and cases of OPD in the Danish Psychiatric Central Register. Offspring registration with AUD was analyzed in relation to parental registration with AUD and OPD. Covariates were offspring gender and parental social status. Results Both maternal and paternal registration with AUD significantly predicted offspring risk of AUD (odds ratios 1.96; 95% CI 1.42-2.71 and 1.99; 95% CI 1.54-2.68, respectively). The association between maternal, but not paternal, OPD and offspring AUD was also significant (odds ratios 1.46; 95% CI 1.15-1.86 and 1.26; 95% CI 0.95-1.66, respectively). Other predictors were male gender and parental social status. A significant interaction was observed between paternal AUD and offspring gender on offspring AUD, and stratified analyses showed particularly strong associations of both paternal and maternal AUD with offspring AUD in female cohort members. Conclusions Parental AUD was associated with an increased risk of offspring AUD independent of other significant predictors, such as gender, parental social status and parental psychiatric hospitalisation with other diagnoses. Furthermore, this association appeared to be stronger among female than male offspring. The results suggest that inherited factors related to alcoholism are at least as important in determining the risk of alcoholism among daughters as among sons.