Abstract: The effcts folow-lead exposure on neurobehavior and hyperactivity in 360 inner-city school children were assessed by measuring he blood lead (PbB), air lead level and FEP、serotonin (5-HT)、dopamine (DA)、no radrenaline (NE)in whole blood.180 children living near abusy road are exposed to lead and 180 are as controls.All were given a neurobehavioral core test battery (WHO recommended neurobehavioral test battery, NCTB).Hyperactivity was quantified by using Co nner's teacher and parent's questio nnaire.As compared with the control group, the exposed group showed sig nificantly higher air-lead level 、blood-lead level、FEP and lower 5-HT level.The children with blood lead level≥10g/ dl were 59.17 %(66.67% in the ex posed group and 57.67% in the control group).Analy sis of the children's neurobehavio ral test performance showed the elevated lead levels (PbB ≥10μg/dl)were.associa ted w ith deficits in visualmo tor functioning 、visual-perceptual capacity and mood states.Hyperactivity was significantly increased with elevated bloo d lead lev els in the children.The children with PbB <10μg/ dl、FEP ≥ 50μg/ dl had deficit in visualmemory and attention.Thus, w e suggest the blood lead be 10μg/ dl as the definitio n of the children lead toxicity.THe children with PbB <10μg/ dl, FEP≥50μg/dl should also be prevented from lead to xicity.