Attention deficit-hyperactivity disorder (ADHD) is known to have neuropsychological consequences that are evident from psychological tests and measures of school failure. However, most available data are based on studies of preadolescent children. For a developmental perspective, older (> or = 15 years) and younger (< 15 years) children with ADHD were assessed. Participants were 118 male participants, ages 9 to 22 years, with ADHD and 99 male controls. Younger and older probands with ADHD were significantly impaired on the Wisconsin Card Sorting Test (WCST), the Stroop test, and the Rey-Osterrieth Complex Figure, regardless of various psychiatric and cognitive comorbidities. Longitudinal research is needed to test the hypothesis that neuropsychological dysfunctions persist in ADHD into adulthood.