Individual differences among substances abusing adolescents should be taken into account when developing a tailored treatment plan. Specifically, whether or not the youth has been diagnosed with an Attention Deficit-Hyperactivity Disorder (ADHD) may influence the youth's experience in treatment. Subjects were 30 ADHD and 30 non-ADHD previously discharged white male clients selected from an adolescent residential substance abuse treatment program. In particular, it was hypothesized that ADHD clients would have significantly different and less desirable treatment outcomes, as well as shorter lengths of stay. Data were collected by sequentially reviewing file records of previously discharged clients. Data did not support the first hypothesis, but a significant difference was observed in terms of actual length of stay in residential treatment. Implications for possible treatment needs of ADHD clients and future research are discussed.