OBJECTIVE To study the reliability of two ELISA kits for detecting IgM antibody against hepatitis E virus (HEV). METHODS Serum samples from 92 healthy subjects, 71 cases suspected of hepatitis E, 55 patients with confirmed diagnosis of acute hepatitis E, 50 individuals with rheumatoid factor (RF) positive and 54 persons with anti-HAV IgM positive were detected with three hepatitis E diagnostic kits. MP-IgM (MP, Singapore), Wantai-IgM and anti-HEV IgG (Wantai, China). HEV RNA was analyzed with RT-PCR in 52 of 71 cases suspected of hepatitis E. RESULTS In healthy subjects,cases suspected of hepatitis E and confirmed acute hepatitis E, the concordance between the two anti-HEV IgM reagents was 73.39% (160/218) and the significant differences in the positive rates of two assays were not observed [46.79% (102/218) vs 44.04% (96/218), chi2 = 0.62, P > 0.05]. Of 71 patients suspected of hepatitis E, the sensitivity for diagnosing acute hepatitis E of Wantai-IgM and MP-IgM were 83.08% (54/65) and 78.46% (51/65) (chi2 = 0.16, P > 0.05), respectively. Among those suspected of hepatitis E with HEV RNA positive, the sensitivity of Wantai-IgM was obviously higher than that of MP-IgM [(97.14%, 34/35) vs (74.29%, 26/35), chi2 = 4.9, P < 0.05]. 48 of 55 patients (87.27%) with confirmed diagnosis of hepatitis E were Wantai-IgM positive while 37 (67.27%) was MP-IgM positive (chi2 = 4.0, P < 0.05). The specificity of Wantai-IgM was higher than MP-IgM [100.00% (202/202) vs 89. 11% (180/202), chi2 = 20.05, P < 0.005]. RF and anti-HAV IgM might cause MP-IgM false positive without interference on Wantai-IgM. CONCLUSIONS Wantai-IgM should be a good ELISA kit for the diagnosis of acute hepatitis E.