Objective: The main aim of this study was to prove the efficacy of an intervention based on board games on executive functions (EFs) and clinical symptoms in children with attention-deficit/hyperactivity disorder (ADHD). Materials and Methods: A nonblinded randomized controlled trial was conducted with a sample of children with a diagnosis of ADHD (diagnosed by psychiatrists and clinical psychologists in a mental health center). Children were randomly allocated by matching age and sex, into two groups: experimental EF training group (n = 13; mean [M]age = 9.46, standard deviation [SD] = 1.20; boys = 53.8%) or a wait-list control group (n = 14; Mage = 9.50, SD = 1.09; boys = 71.4%). Measures assessed individually at pretest, posttest, and follow-up intervention included EFs and clinical symptoms. Results: Analysis of covariance repeated measures analysis showed that linguistic short-term memory, F(1,28) = 7.45, p = 0.02, and conduct problems, F(1,28) = 12.51, p = 0.00, significantly improved with larger effects in the board games training group after intervention when compared to the wait-list group. Although nonsignificant effects were reported at the follow-up, large effect sizes were actually found. Conclusion: Although future studies are needed, the results of this study highlight the importance of board games and its efficacy as a possible therapeutic and/or preventive intervention on ADHD. Keywords: ADHD, Board games, Working memory, Executive functions, Conduct problems