The DSM-IV ADHD is comprised with three subtypes, predominantly Inattentive (ADHD-I), predominantly Hyperactivity/Impulsivity (ADHD-H), and Combined subtype (ADHD-C). The DSM-IV field trials indicate that the current subtypes differ significantly on variables such as age of onset, gender ratio, and level of social and academic impairment (Lahey et al., 1994). Although previous researches have suggested that neuropsychological deficits in ADHD are associated with frontal-subcortical regions (Castellanos, 1997), few studies have addressed whether the DSM-IV subtypes differ neuropsychologically with inconsistent results (Nigg et al, 2002).