Background and Purpose: Children with Attention Deficit Hyperactivity Disorder (ADHD) experience many problems in executive functions which later may result in numerous negative consequences in different dimensions. Therefore, this study was conducted to investigate the effectiveness of parent based metacognitive executive functions training on behavioral symptoms and cognitive functions of children with ADHD.
Method: This study was quasi-experimental in the methodology with a control group pretest-posttest design. The population included all the 1^st to 3^rd grade primary school students aged 7 to 10 in Tehran in the academic year 2018-2019. Among them, 40 students together with their mothers were selected by purposive sampling and then randomly divided into the two groups, the experimental and the control group. Mothers of the experimental group received twelve 2-hour sessions of metacognitive executive functions training whereas the mothers in control group (n=20) were placed in the waiting list. SNAP-IV Rating Scale (Swanson, Nolan and Pelham, 1983) and CNS Vital Signs Neurocognitive Assessment (Gualtieri & Johnson, 2006) were used to gather the data. Then, data were analyzed by Multivariate analysis of covariance (MANCOVA).
 Results: Results showed that metacognitive executive functions training was significantly effective in decreasing the behavioral symptoms (F=24.782) and increasing the cognitive functions (working memory: F=32.130 and cognitive flexibility: F=6.053) of children with ADHD. 
Conclusion: By using game based activities structurally managed by the parents, this therapeutic method targets dimension of executive functions which are important in the management of cognition and behavior; hence it can improve the cognitive and behavioral symptoms in children with ADHD.