Abstract Hair samples of 25 children with mild mental subnormality, 25 children with moderate mental subnormality and 25 children with attention deficit hyperactive disorder (ADHD) were collected and analyzed by atomic absorption spectrophometry for determination of their content of lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn). The results were compared with hair content of the studied metals of 75 healthy children. A highly significant increase in lead scalp hair content was observed in both groups of mental retardation (MR) and in ADHD group when compared to controls. No difference was observed regarding the other metals between different groups. A negative correlation was found between hair Pb and Intelligence Quotient (IQ). Also, a positive correlation between scalp hair lead and total aggression score was discovered. Conclusion: Both mentally retarded & ADHD children have more Pb content than controls. Monitoring scalp hair metals content provides a valuable screening method for assessment of environmental pollution in children.