OBJECTIVE: The Child Behavior Checklist-Dysregulation Profile (CBCL-DP), characterized by elevated scores on the "Attention Problems," "Aggressive Behavior," and "Anxious/Depressed" scales in the CBCL, has been associated with later severe psychopathology. In a sample of children with ADHD, this study sought to further explore the clinical characteristics, the response to methylphenidate medication, and the cognitive features of ADHD children with CBCL-DP. METHOD: The sample consisted of 173 ADHD outpatients (age = 10.9 ± 2.81) assessed using symptom severity scales, personality questionnaires (Emotionality Activity Sociability [EAS] and Junior Temperament and Character Inventory [JTCI]), and neuropsychological tests. A subsample of 136 participants was reassessed after optimal adjustment of methylphenidate dosage. RESULTS AND CONCLUSION: Variables that were independently associated with CBCL-DP were clinical severity (ADHD Rating Scale [ADHD-RS]), internalized disorders, high emotionality (EAS), and low self-directedness (JTCI). CBCL-DP was associated neither with poorer response to methylphenidate nor with more side effects. There were no differences in cognitive performances between participants with and without CBCL-DP.