Abstract: Objective To study the effect of lead exposure on mimune function of pigs.Methods Twenty-fourpigs were randomly divided into four groups and were fed for 90 days with normal feeds and feeds with lead content of 5 mg/kg(low dose),15 mg/kg(medium dose),45 mg/kg(high dose),respectively.The number of white blood cell(WBC)and IgM,IgG IgA,C3,C4 level in serum were measured and Tlym phocyte activity was determined by MTT method.Results Tlym phocyte activity in low dose group decreased by 29.3% compared with the control group(P<0.05).The content of IgA and Tlym phocyteactivity in the medium dose group decreased by 0.12 g/L and 25.2%,respectively,compared with the control group(P<0.05).The content of WBC,IgM,IgG IgA and C3 in high dose group decreased by 4.3&109/L,1.48 g/L,0.13 g/L,0.4 g/L,0.31 g/L,respectively.While the Tlylnpho cvte activity was 37.4% lower than that of the control group,and all the differenes compared with the control group were statistical significan t(P<0.05).Conclusion The mimunity of pigs could be affected by lead in feed when its content was up to 5 mg/kg,and could be signincantly de reased with the lead content above 45 mg/kg.