Objective To evaluate the significance of AFP-IgM, this is one of new tumor markers, in the diagnosis of primary hepatocellular carcinoma (PHC). Methods The contents of AFP-IgM and AFP in serum of 103 healthy subjects, 74 patients suffered primary hepatic carcinoma, 27 patients affected by liver cirrhosis and 63 patients affected by chronic hepatitis were detected by means of enzyme linked immunosorbent assay and electrochemiluminescence. No-PHC is comprised of liver cirrhosis,chronic hepatitis and health subjects as control group. Results The area under ROC curve of AFP was larger than that of AFP-IgM (0.85 vs 0.72, Z=3.21) and the best cut-off value of AFP-IgM and AFP was 3×105-AU/L and 10 ug/L respectively, which was determined by ROC curve. Under the cut-off value, the sensitivity of AFP- lgM and AFP for PHC were 64.9% and 79.7%, and the specificity were 75.6% and 80.3%, yet their efficacies were similar. However, for early diagnosis of liver cancer (stage Ⅰ and Ⅱ), the area under ROC curve of AFP-IgM was larger than that of AFP (0.91 vs 0.82,Z=1.73). The sensitivity of AFP-IgM andAFP were 94.4% and 72. 2%, and the specificity were 81.9% and 79.9%. The differences of AFP-IgMand AFP for early diagnosis of liver cancer were statistically significant. When both of the test results combined AFP-IgM with AFP are positive, it can be diagnosed as liver cancer. The specificity of combineddetermination of the two forms was 89.1%, and the efficacy was 79. 0%. Conclusions Both of thesensitivity and specificity of the AFP-IgM test were higher than that of the AFP for early diagnosis of livercancer. We also found that combined determination of the two forms significantly increased the specificityand the positive predictive value for the diagnosis of PHC, thus AFP-IgM was of especially significance forearly diagnosis of liver cancer.