Objective: This study aimed to look at the differences in SPECT findings at baseline and concentration between ADHD children and adolescents who endorsed high aggression symptomatology and those who endorsed low aggression symptomatology. Method: Participants were 701 ADHD children and adolescents with high aggression (M age = 12.24, SD = 3.18, male = 70%, Caucasian = 51%) and 710 ADHD children and adolescents with low aggression (M age = 12.01, SD = 3.24, male = 75%, Caucasian = 52%). Subjects were selected in the high and low aggression groups depending on their endorsement of aggression symptomatology. The seventeen brain regions analyzed included the limbic area, basal ganglia, cerebellum, frontal areas, occipital areas, parietal areas, temporal areas, motor-sensory areas, and the vermis. Results A MANOVA found significant differences for the cerebellum (right and left), frontal (right and left), parietal (right and left), motor sensory (right and left), and right temporal regions (p < .01). No significant differences were found at baseline. Conclusion Results suggest that the functional abilities of these regions are implicated in children and adolescents with ADHD and high aggression, and this may account for their difficulties in executive functioning and self-regulatory processes. No differences were found in the limbic regions, and this suggests that the emotional circuits that are deregulated in pure aggressive children may not be dysregulated in ADHD children with high aggression symptomatology. Differences were only found at concentration. This implies that the dysregulation of the specific areas of the brain occur only during tasks that require sustained attention.