Procedural design Parents of children referred to the clinic for ADHD diagnosis and management will be offered to participate in the study. After the parents and participant signed the proper consent form a meeting for evaluation by a psychiatrist will be scheduled. If indeed an ADHD diagnosis is made and methylphenidate treatment is recommended the children will be recruited for the study. The treatment design will be double-blind placebo controlled cross-over. Half of the patients will receive methylphenidate immediate release (IR) first and then placebo and half will receive placebo first and then methylphenidate-IR in a randomized manner. The placebo and methylphenidate-IR pills (identical in appearance) will be placed for each subject in the study group in two cases marked "A" an "B", the content will be written by an RA separately which will decide the order (first placebo or first methylphenidate-IR) using a coin flip, and will be revealed only after the final session and after all questioners will be filled.