A diffusion tensor imaging (DTI) study was conducted in 12 adolescents with attention deficit/hyperactivity disorder and 14 age- and IQ-matched healthy controls. Inter-subject comparison of fractional anisotropy (FA) of the whole brain between the groups was obtained using the tract-based spatial statistics method. Results revealed significantly lower FA in widespread white matter tracts in cases relative to controls. Also, the FA measure of identified regions was associated with cognitive performance.