As mercury absorbed into body can cross the blood-brain barrier and react with DNA and RNA. Central nervous system has been known to be affected especially in children. But it was very difficult to know the influences of chronic low-does Hg exposure on the health. Although many studies investigated the affect, most of results were still disparate. In order to investigate the health effects of mercury exposure, several test were conducted for some Korean school children. The general health effects were investigated using blood test, Posturography and computer-based neurobehavioral test was done to examine the affect of Hg into neural responses. About 400 children were chosen for blood test whose blood Hg level were upper and lower 10% of population participated in the nationwide Hg exposure survey. The concentration of calcium and creatine, the number of white and red blood cell showed statistical significance with Hg exposure in blood test. Another 36 children were selected from the same participants for the posturography and neurobehavioral test. The intensity and center frequency of hand tremor which were related to unconsciousness also showed distinct significances. Any general relations with Hg exposure were not found in all test including computer-based neurobehavioral test.