Electroencephalography (EEG)-neurofeedback has been shown to offer therapeutic benefits to patients with ADHD in several mostly uncontrolled studies with relatively small sample sizes. It is unknown how EEG-neurofeedback affects brain functioning and exerts therapeutic effects in ADHD. This study is designed to examine the efficacy and safety of EEG-neurofeedback in a scientific rigorously way and to study the underlying neurobiological mechanisms of EEG-neurofeedback.