In a multicentre randomised controlled trial, we evaluated the clinical efficacy of neurofeedback (NF) training in children with ADHD and investigated the mechanisms underlying a successful training. We used an attention skills training, coupled with the training setting and demands made upon participants, as the control condition. At the behavioural level, NF was superior to the control group concerning core ADHD symptomatology as well as associated domains. For the primary outcome measure (improvement in the FBB-HKS total score), the effect size was .60. The same pattern of results was obtained at the 6-month follow-up. Thus, NF may be seen as a clinically effective module in the treatment of children with ADHD. At the neurophysiological level (EEG, ERPs), specific effects for the two NF protocols, theta/beta training, and training of slow cortical potentials were demonstrated. For example, for theta/beta training, a decrease of theta activity in the EEG was associated with a reduction of ADHD symptomatology. SCP training was accompanied inter alia by an increase in the contingent negative variation in the attention network test; thus, children were able to allocate more resources for preparation. EEG- and ERP-based predictors were also found. The present article reviewed the findings of the original papers related to the trial and outlines future research topics.