This study was conducted to determine the effect of Nintendo Wii-based motor and cognitive training on motor proficiency, visual attention, and cognitive flexibility of children with attention-deficit/ hyperactivity disorder. Thirty boys with ADHD, aged 8-11 years, were selected from the Avand development center and were randomly assigned to an experimental and control group. The experimental group participated in a selected gaming program for 24 sessions, 60 minutes per session. At the beginning of the study and after eight weeks of intervention, participants were assessed with the Bruininks-Oseretsky test of motor proficiency and trail making test. R Statistical software was used for data and analysis Multivariate analysis of covariance (MANCOVA) was used to test differences between groups. For all statistical analyses significance was set at 0.05. The results of the post hoc contrasts on MANCOVA showed that balance (p = 0.01), upper limb coordination (p = 0.01), bilateral coordination (p = 0.02), strength (p = 0.06), response speed (p = 0.02) and manual dexterity (p = 0.003) components, in the experimental group were significantly improved in comparison to the control group, But there were no significant differences between groups in running speed and agility (p = 0.09) and visual-motor control (p = 0.27). A significant difference was also found between groups in cognitive flexibility (p = 0.01). Our findings suggest that Nintendo Wii game playing might be a simple and cost-effective way for improving motor proficiency and cognitive flexibility of ADHD children.