Background: Attention Deficit Hyperactivity Disorder (ADHD) is considered one of the most common childhood psychiatric disorders. The worldwide prevalence is approximately 5%. In Egypt, exposure of children to heavy metal is considered one of the risk factors lead to ADHD. The aim of this study was to investigate the potential association between lead exposure and ADHD in children and find the association between the level of exposure to lead and degree of ADHD symptoms. Method: Case control study was done by random selection of children from outpatient Clinic at Assiut University Hospital of Children. Data were collected by a questionnaire to evaluate environmental exposure to lead and blood analysis for this heavy metal level. Results: Lead level in ADHD children was significantly higher than control (20.88± 7.47 ug/dl versus 16.13 ± 7.91 ug/dl). While there is no significant difference between lead level and degree of symptoms among the ADHA children. In conclusion, there is a significant association between ADHD in the examined sample of children and exposure to lead especially through water contamination with lead. Lead level is significant for reflecting exposure to lead.