Objective To discuss the value of detection of Pre S1 antigen(Pre-S1 Ag) of hepatitis B virus. Methods ELISA was used to detect Pre-S1 Ag and HBeAg in serum from 854 HBsAg-positive persons in medical ex-amination who have no symptom. In addition, Pre-S1Ag in serum from 300 random samples of HBsAg-negative persons were detected in medical examination. Results Pre-S1Ag positive rate was 41.1% (351/854) in 854 samples with HBsAg(+) ,and HBeAg positive rate was 26.6% (227/854) in them. Pre-S1 Ag positive rate was 79.7% (181/227) in HBeAg(+) group but was 27.1% (170/627) in HBeAg(-) group. Pre-S1 Ag wasn't detected in 300 samples with HBsAg(-). Conclusions In HBsAg-positive samples who have no symptom,the detection rate of Pre-SIAg is higher than that of HBeAg. Pre-Sl Ag can reflect duplication and infectivity of HBV better than HBeAg and it has more value to epidemiology investigation and clinical diagnosis than the latter.