Thirty-five percent of 298 treatment-seeking cocaine abusers met DSM-III-R criteria for childhood attention deficit hyperactivity disorder (ADHD). Subjects with childhood ADHD were likely to be male (78%), meet Research Diagnostic Criteria (RDC) for conduct disorder (93%) and antisocial personality disorder (47%), and report a history of conduct disorder in first-degree relatives. With respect to those without the disorder and regardless of co-occurrence with sociopathy, cocaine abusers with childhood ADHD were younger at presentation for treatment and reported more severe substance use, earlier onset of cocaine abuse, more frequent and intense cocaine use, intranasal rather than freebase or intravenous use of cocaine, higher rates of alcoholism, and more previous treatment. This pattern of cocaine use is consistent with clinical descriptions of self-medication of residual symptoms of ADHD in cocaine abusers. Data from this study suggest that there may be more cocaine abusers with a history of ADHD than previously recognized in clinical samples of cocaine users, and that these individuals may differ in clinically meaningful ways from those without childhood ADHD. Moreover, the poorer outcome of subjects with ADHD in this sample underlines the importance of identifying and treating residual symptoms of ADHD in cocaine abusers.