Abstract: The structure alerations of spleen in rats with leng term low lead exposure were observed by high power light microscope and transmission electron microscope.The results were as follows:(1)Light microscope of spleen showed that the relative area of boundary zone and the nunber of splenic nodules decreased.(2)Eletron microscope of splenic immune cell indicated that mitochondria were swollen,vaculated and pyknotic;and endoplasmic reticular were swollen and degrannlated.(3)The results suggested that long term low level lead exposure could cause the impairment of splenic immune cell.These would provide a morphologic basis for further studying immunotoxicity of lead.