Global rates of attention-deficit/hyperactivity disorder (ADHD) have risen. In Korea, ADHD is associated with functional impairments and comorbidity with other psychological disorders. This study examined the correlates of ADHD in a psychiatric sample of Korean adolescents on the Minnesota Multiphasic Personality Inventory-Adolescent-Restructured Form (MMPI-A-RF). In a clinical sample of 247 adolescents, MMPI-A-RF scores from 46 patients diagnosed with ADHD were compared to the remainder of the clinical sample and to the Korean MMPI-A-RF norms. Results demonstrated significantly different scores for the ADHD group on scales indicating externalizing concerns and behavior dysfunction compared with the clinical group with other disorders and to a normative sample. Notable differences were also observed between clinical groups on scales reflecting interpersonal functioning. Relative risk ratio analyses demonstrated that an MMPI-A-RF T-score of 55 was generally most effective for predicting risk for an ADHD diagnosis in the clinical sample.