The study was carried out to determine the frequencies of ADHD among Iraqi primary school pupils, and to evaluate the relationship of ADHD with Thyroid Stimulating hormone (TSH), Testosterone and dopamine, recognize the role of some dopamine related genes as, DAT1, DRD2 and DRD4 in ADHD. This study was conducted during the period from the beginning of April 2012 to the end of September 2014.The study sample included 1431 school pupils (777) males, and (654) females with age ranged between 8-12 years, selected from nine primary schools, at Baquba city.