Background: The majority of cognitive and behavioral deficits in children with attention deficit- hyperactivity disorder (ADHD) originate from impaired inhibitory control. Methods: In the present study, thirty preschoolers with ADHD were recruited in a random clinical trial design in two equal control and intervention groups. The Color-Word Stroop test, Go/No- Go task, Swanson, Nolan, and Pelham Rating Scale, and Child Behavior Checklist were used for assessment at baseline, after intervention, and at one- month follow- up sessions. The program for attentive rehabilitation of inhibition and selective attention (PARISA) was used for intervention in 12-15 sessions. Results: The data demonstrate improvement in prepotent inhibition and interference control in the intervention group. Furthermore, the hyperactivity/ impulsivity symptoms were ameliorated and the externalizing behavioral problem were improved after intervention. Conclusion: Inhibitory control in preschoolers with ADHD is trainable and the benefit of training could be transferred to ADHD symptoms and externalizing behavior.Trial registration: IR.IAU.TMU.REC.1398.046.