Objective: To assess the comorbidity of bipolar disorder (BPD) in children with ADHD and to study the psychopathological profile of ADHD children with and without mania. Method: A total of 100 children with ADHD were assessed with a semistructured diagnostic interview and questionnaires of mania, ADHD, and general psychopathology. Results: 8% of children met criteria for BPD and 6% for BPD-not specified. ADHD children with bipolar spectrum disorder had greater comorbidity with disruptive behavior disorders and scored higher on the Young Mania Rating Scales and on the Child Behavior Checklist (CBCL) Scales of rule-breaking behavior, externalizing problems, and total problems; however, significance on the CBCL Scales was lost when controlling for disruptive behavior disorders. Conclusion: BPD is frequently associated with ADHD; it has important implications for prognosis and choice of treatment. Differences on the CBCL Scales could be explained by the comorbidity with disruptive behavior disorders rather than by a specific manic profile. (Contains 3 tables and 2 figures.)