Attention deficit/ Hyperactivity Disorder (ADHD) is a prevalent neuropsychological disorder in children. This research aimed to determine and compare the effectiveness of computer-assisted cognitive remediation (CACR) and Psycho stimulant drug in improving clinical symptoms of children with ADHD. The research design was pretest, post-test, and follow-up with two experimental groups. 23 ADHD children were selected by convenience sampling and inclusion- exclusion criteria. Two groups were matched according to the severity of their disorders and randomly assigned to drug therapy (n= 11) and CACR (n= 12) groups. The research tools were including Persian version of SNAP-IV scale, the short form of WISC-R and child syndrome inventory (CSI-4). The data were analyzed by RM-MANOVA, Mixed design ANOVA. The CACR had effective and enduring variation on clinical symptoms of ADHD. CACR in comparison to the Drug therapy had more and enduring effect to improve clinical symptoms; but that was non-significant. Altogether, the effectiveness of cognitive trainings in improving motivational/motor symptoms was more than cognitive symptoms. Therefore, CACR can be used as an alternative technique of the psycho stimulant drugs in treatment of ADHD.