Abstract: Objective To explore the effects of lead on the transcription factor Brn 3a and neuro filament proteins(NF) in the neurons of central nervous system.Methods The pregnant rats were randomly divided in to 4 groups treated with distilled water,0.5,1.0,2.0 g/L lead actate solution viadrinking water,respectively.The lead exposed period for exposure groups was from the 15th day after pregnancy to the 21th day when the off spring began to wean.Tissues o f various brain regions were obtained and Brn 3a and NF proteins expression level were observed by immunoh istochemistry method.Results The Brn 3a decreased significantly in lead poisoning groups compared with that of control group(P<0.05 or P<0.01).The prote in level of NF decreased in cortex,the hippocampus and the cerebullum in high dose Pb exposed rats(P<0.05 o r P<0.01).Conclusion Lead exposure could decrease the Brn 3a expression and reduce the expression of NF.