Attention deficit hyperactivity disorder (ADHD) is a common neuropsychiatry disorder with several key symptoms, such as inattentiveness, impulsivity and hyperactivity. Neuropsychiatry studies have implicated the frontostriatal circuit in the pathological physiology of the disorder. Using magnetic resonance imaging (MRI), we examined the basal ganglia in 13 ADHD patients and eight unaffected comparison children. The volume of caudate, putamen and globus pallidus was measured. In the ADHD patients, we detected an increased left > right asymmetry of the basal ganglia. This reversal of asymmetry in the globus pallidus and caudate nucleus were statistically significant. These finding provide further evidence of morphological brain abnormalities in ADHD.