OBJECTIVE: To study the effects of exposure to low level lead on neurobehaviors of preschool children. METHODS: Blood lead levels were measured in 211 preschool children aged 4-6 years in a kindergarten without known exposure to lead sources; the 211 children were assigned into two groups: low blood lead level group (LL group, <100 μg/L ) and high blood lead level group (HL group, ≥100 μg/L). Their neurobehaviors were assessed with Achenbach child behavior checklist (CBCL) to study the relationship between blood lead and CBCL total behavior scores (TBPs), internalizing and externalizing scores (Ints and Exts).RESULTS:The Exts and incidence of abnormal behavior problems in the HL group ( 13.28 ± 6.26 and 18.26% , respectively) were much higher than those in the LL group ( 9.98 ± 5.46 and 7.29% , respectively)(t= 4.0677 , χ 2= 5.470 , P< 0.05 ). The blood lead level was positively correlated significantly with the scores for hyperactivity, attack and disobedience (r= 0.3164 , 0.2828 , 0.1886 , P< 0.05 ). When the blood lead levels of children reached or exceeded 150 μg/L, the incidence of abnormal behavior problems increased significantly. CONCLUSIONS: Low level lead exposure can have adverse effects on neurobehaviors of preschool children.