This study examined the relationship between familial history of substance use and addiction severity and treatment outcomes of opiate-dependent patients. The sample was comprised of 281 methadone maintenance patients at a VA or community-based clinic. Using the family history section of the Renard Diagnostic Interview, three familial risk groups were identified based on patients' self-report of their relatives' substance use. The three groups considered both the number and type (e.g., first vs. second degree) of biological relatives with a substance use problem. These three risk groups included: (1) high risk (HR, n = 111), (2) medium risk (MR, n = 80), and (3) low risk (LR, n = 90). HR patients reported a history of more severe asocial behavior at baseline and they reported more medical problems and a greater degree of concurrent alcohol use both prior to and after 6 months of treatment compared to LR patients. In addition, the HR group reported more family/social problems at baseline compared to the MR and LR group and both HR and MR patients reported more psychological problems than LR patients after 6 months of treatment. However, when accounting for baseline differences, the regression analyses demonstrated that familial risk was not predictive of drug treatment outcomes after 6 months of methadone maintenance treatment.