Objective: Using an offspring-of-twins design, we tested the hypothesis that exposure to paternal alcoholism during the child's first 12 years will increase offspring risk for subsequent alcohol-use disorders (AUD). Method: Structured psychiatric interviews assessed history of psychiatric and substance-use disorders in Vietnam Era Twin Registry fathers (n = 512), their offspring (n = 877), and mothers of the offspring (n = 507). Exposure was defined as the fathers' endorsement of any Diagnostic and Statistical Manual of Mental Disorders (DSM), Fourth Edition, AUD symptom, according to the Lifetime Drinking History assessment (administered in 1999), at any time between offspring ages 0-12 years; all fathers had satisfied DSM, Third Edition, Revised (DSM-III-R), criteria for alcohol dependence in a 1992 diagnostic interview. Cox proportional hazards models were fit to predict time to first symptom of abuse/dependence in offspring. Results: Offspring exposed to paternal alcoholism were significantly more likely to develop an AUD when compared with offspring of nonalcoholic fathers (hazard ratio [HR] = 1.51; 95% confidence interval [CI]: 1.10-2.07). Although offspring unexposed to paternal alcoholism did not significantly differ from control offspring (HR = 1.50, 95% CI: 0.93-2.41), the magnitude of association was similar to that in the exposed offspring. There were no significant differences in AUD between offspring of alcoholics who were exposed and those who were not exposed to paternal alcoholism, as long as fathers had satisfied DSM-III-R criteria for alcohol dependence at some point in their lives. Conclusions: There does not appear to be a relationship between exposure to paternal alcoholism during childhood and development of an AUD in offspring. Genetic and high-risk environmental factors that are correlated with lifetime paternal alcoholism may be stronger predictors of offspring AUD than fathers' problem drinking. Future research should be encouraged, using more comprehensive analyses, to examine the role of family genetic influences and other family environmental influences on offspring alcohol outcomes.