Exposure to mercury was assessed in schoolchildren 7-13 years of age (n=274) using urine mercury analysis. The arithmetic mean (AM) and geometric mean (GM) of total urinary Hg were measured as $2.66{pm}1.12;{mu}g$/g-ct and $2.22{pm}1.68;{mu}g$/g-ct, respectively, for 274 school children. GM of urinary Hg level was $2.11{pm}2.00;{mu}g$/g-ct for male and $2.33{pm}2.70;{mu}g$/g-ct for female. The influence of independent factors on the total urinary mercury (Hg) level was evaluated utilizing a multiple regression analysis to find a possible correlation with urinary Hg concentration. Independent factors are such as: (1) gender; (2) age; (3) location (inland and coastal); (4) school; (5) nearness to traffic road and industrial complex; (6) residential house types; (7) preference of fish (8) frequency of fish intake (8) amalgam; (9) medication and (10) smoking status as independent variables. The most statistically important cofactors turned out were school location, age and daily fish consumption. Amalgam fillings did not affect any relevance to mercury concentrations in urine, while daily fish consumption was associated with the increasing amount of fish consumed, in females alone. The statistical significance of the effect of each variable was calculated through T-test, which has shown specific statistical significance among co-founding variables. As a result, the natural logarithm of urinary Hg showed a weak correlation with age ($r^2$=0.085).