Background Young people with attention deficit hyperactivity disorder (ADHD) often have learning and behavioral control difficulties. Aim The aim of this review is analyse the acute and chronic effect of physical activity (PA) on the cognition and behaviour of children and adolescents with ADHD. Methods Studies were identified in five databases (PubMed, SPORTDiscus, ProQuest, Web of Science, and SCOPUS), from January 2000 through to January 2017. A total of 16 interventional studies met the inclusion criteria. Results/conclusions PA practice of 20–30 min (intensity 40–75%) produces a positive acute effect on processing speed, working memory, planning and problem solving in young people with ADHD. However, these effects on behaviour are contradictory and vary depending on age. Chronic PA practice (≥30 min per day, ≥40% intensity, ≥three days per week, ≥five weeks) further improves attention, inhibition, emotional control, behaviour and motor control. The results must be treated with caution, because only 25% of the studies used confounders. Implication More research is needed to justify the causes of these effects. It is necessary to establish programs with regard to the duration, intensity, kind of exercise, and time of PA to improve cognition and behaviour in young people with ADHD taking into account potential confounders.Keywords Physical exerciseAttention deficitCognitive performancePhysical fitnessAdolescentConfounder