Abstract: Objective To explore effects of exposure to rare earth elements(REEs)on function of immune system of children.Methods IgA,IgG,IgM and complement C3,C4 in blood serum were determined with turbidimeter measure in 205 children aged 7-10 years,living in rare earth ore containing area and the control area in Jingxi,China.IgE in 70 blood serum samples(35 samples from exposure to REEs group and 35 samples from the control group)were determined by chemiluminescence immunoassay(CLIA).Lymphocyte subset CD₃⁺,CD₄⁺,CD₈⁺,CD₄⁺/CD₈⁺,and NK in 37 blood samples were determined by flowcytometry(17 samples from exposure to REEs group and 20 samples from the control group).While fifteen kinds of REEs in 112 blood samples(69 samples from exposure to REEs group and 43 samples from the control group)were determined by inductively coupled plasma source mass spectrometry(ICP-Ms).Results All 15 kinds of REEs were detected in each sample.The quantity of blood REEs of the children in the rare earth area(2.18±1.08ng/g)is 1173 times as that of the children in the control area(1.26±0.35ng/g).The difference is significantly great(P<0.01).The humoral immunity would be changed in the body of the children exposed to REEs,the quantity of IgM(0.87±0.21g/L)was lower in exposure group than in control group(0.94±0.18g/L,P<0.05).The quantity of IgG,IgA,C3,C4 were no significant difference in tow group.The measuring result of T lymph subgroup of the children indicates:CD₃⁺,CD₄⁺,CD₄⁺/CD₈⁺ changed a lot.The percent of CD₃⁺(54.05%±7.55%),CD₈⁺ (22.65%±5.18%)were significantly lower and CD₄⁺/CD₈⁺ (1.38±0.36)was significantly higher in expousure group than in control group(CD₃⁺:62.84%±7.05%,CD₈⁺:29.25%±3.90%,CD₄⁺/CD₈⁺:1.12±0.18).Multiple regresion analysis showed the variable of blood REEs in expousre to REEs group or those in the control group were introduced into the IgM regression model.The standardized partial regression coefficient obtained was equal to -0.296.Conclusion Exposure to REEs could interrupt the function of immune system in children.