Early studies examining the relationship of personality disorders to opiate addiction attempted to define an "addictive personality." Later research found that personality disorders in opiate addicts were common but heterogeneous. We examined whether different comorbid personality disorders have prognostic specificity. Rates of depression and alcoholism as well as assessments of specific problems were measured in a 2.5-year follow-up of 150 treated opioid addicts. Using DSM-III criteria, we found that borderline personality disorder predicted more depressive disorders and alcoholism at follow-up; yet greater recovery from these disorders was seen. Borderline patients had more severe psychiatric problems as measured by the Addiction Severity Index. Other ASI outcomes differed by personality disorder; antisocial addicts had more legal problems, and narcissistic addicts had more medical problems. These results suggest that treatment for opiate addicts be tailored to the specific needs of the patients, which can be predicted, in part, by their comorbid personality disorder diagnosis.