While there has been much recent interest in the relationship between attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUDs), little has been reported about ADHD diagnostic subtypes, persistence of symptoms from childhood into adulthood, and substance of choice in individuals with substance use disorders (SUD+) and comorbid ADHD. To examine the prevalence and subtypes of ADHD in a group of SUD+ individuals, 136 inpatients with an SUD diagnosis (cocaine vs. alcohol vs. cocaine/alcohol) were administered a structured interview for ADHD. Of the SUD+ individuals, 32% met criteria for ADHD, and 35% of those with a childhood diagnosis of ADHD continued to have clinically significant symptoms into adulthood. There were no significant differences in the percentage of ADHD between the SUD+ groups divided by drug choice. Of ADHD subtypes, subjects with combined and inattentive types were significantly more likely to have symptoms continue into adulthood (p < or = .05) than the hyperactive/impulsive subtype. Patients with cocaine use were more likely to have ADHD in childhood only when compared to the alcohol or cocaine-alcohol groups. The findings of this study indicate that ADHD is prevalent in treatment-seeking substance users without difference in prevalence or subtype by drug choice.