Background: Many, but not all, types of antisocial personality disorders (ASP) are complicated by alcohol dependence. Therefore, some additional risk factors may exist for alcohol dependence co-occurring with ASP. We studied whether severe childhood conduct disorder and a family history of alcohol dependence are possible risk factors for the development of alcohol dependence in ASP. Methods: The subjects were 81 male Japanese criminals diagnosed with DSM-III-R ASP. Relative risks of alcohol dependence for severe conduct disorder and for a positive family history were estimated by using a multiple logistic model. Results: Forty-three subjects (53.0%) met criteria for DSM-111-R alcohol dependence. The relative risk of alcohol dependence for severe conduct disorder (n= 44), compared with mild conduct disorder, was 4.1; whereas the relative risk for a positive family history (n= 31), relative to a negative family history, was 1.9. Severe childhood conduct disorder was also associated with severe adulthood antisocial behavior and an earlier onset of alcohol dependence. Conclusions: The results suggest that severe childhood conduct disorder and a positive family history of alcohol dependence are independent premorbid risk factors for developing alcohol dependence among persons with ASP.