The present study aimed to investigate the relationship between the level of mercury in urine and the hyperactivity of children in preschool age.in Alexandria city  A random sample included 200 children (100 from contaminated areas, and 100 from  non-contaminated areas). was taken in the study Also subsample have been chosen (10 For each area)  to estimate the concentration of mercury in the urine of children.
Data were collected through personal interview questionnaire with children mothers.
The most important results could be summarized as follows:
Personal and Household Characteristics:
1-    46 % of the mothers from non-contaminated areas had high institute education, compared with 12% only of the mothers at contaminated areas, the differences were significant (P ≤ 0.01)
2-    94% of the mothers in  contaminated areas were house wives, compared with 48% in   non-contaminated areas, the differences were significant (P ≤ 0.01).
3-    Only 8% of the fathers in contaminated areas have high level of education, compared with 49% of the fathers in  non-contaminated areas.
4-    Income per capita (average of the monthly income) in   non-contaminated areas was higher than contaminated areas (608.65 ± 337.58, 248.87 ±101.09) LE respectively, the differences was significant (P ≤ 0.01).
 5-    100% of the mothers in non-contaminated areas said gestational age of the child ranged between 36> 40 weeks, compared with 97% in contaminated, the differences  were not significant between the two groups.
6-    The average birth weight in contaminated areas was (2.97 kg ± 0.42) compared to (3.23 kg ± 0.54) in non-contaminated areas, the differences was highly significant (P ≤ 0.01).  Income per capita (average of the monthly income) in non-contaminated areas was high her than contaminated areas (110.14 ±61.14, 77.4 ±58.23)LE  respectively, the differences was significant (P ≤ 0.01).
7- The concentration mean of urine mercury was 3.64± 0.558 µg/l in contaminated areas, compared with 1.94 ± 0.433 µg/l in non-contaminated areas. The differences were highly significant (P ≤ 0.01).
8- For ADHD the results revealed that children in contaminated areas had high   scores than children in non-contaminated areas; the differences were highly significant (P ≤ 0.01).
9-The results of the correlation coefficients among some variables indicated that there were a negative significant correlation (P≤ 0.01) between educational status of the Parents and Professions, income per capita, the Gestational age of the child and urine mercury concentration.
10-Also, there was a positive highly significant correlation (P≤0.01) between the child's age, the order of the child and the concentration of mercury in the urine of children.
Therefor it is recommended to held awareness programs to mother about sources of pollutants especially mercury, and how to avoid exposure to these sources in order to keep their children healthy.