Objective To compare the performance of two commercially available ELISA kits for detection of diphtheria IgG antibody to provide data for the proper kit choice. Methods Thirty-three serum samples from staff of the capital airdrome and two standard sera were tested for the evaluation of the kits.Commercial ELISAs were compared with respect to their reproducibility(intra-assay variation and inter-assay variation)and accuracy.Results For the detection of standard serum,intra-assay variation(Coefficient of Variation,CV)was 13.5507% for IBL kit and 5.9541% for Virion kit,the inter-assay variation(CV)was 9.9890% for IBL and 2.4728% for Virion kit.For the serum sample,intra-assay variation(CV)was 14.5270% for IBL and 11.0612% for Virion,the inter-assay variation(CV)11.0039% for IBL and 8.1506% for Virion kit.For the detection of standard serum,inter-assay variation(CV)was 9.9890% for IBL and 2.4728% for Virion.The accuracy was analyzed by variation between the actual concentration and measured concentration of standard serum,the CV was 17.6889% for IBL and 1.3966% for Virion.Conclusion The intra-assay and inter-assay variation of the two kits are generally acceptable(CV