150 specimens were collected from chronic hepatitis patients, asymptomatic hepatitis B surface antigen (HBsAg) carriers and healthy individuals. Serum Pre-S1 and HBV markers were determined by enzyme immunoassay (EIA) and HBV DNA was tested by polymerase chain reaction (PCR). According to the results, specimens could be classified into five different groups: HBsAg and hepatitis e antigen (HBeAg) both positive; HBsAg positive and HBeAg/anti-HBe both negative; HBsAg and anti-HBe both positive with HBeAg negative; HBsAg negative with positive antibodies to s, c and e antigens; negative in all HBV markers. Each groups comprised 30 specimens respectively. The positive rate and relative titer (sample A value/cut-off value) of Pre-S1 Ag in HBeAg positive group (66.6%, 4.3250 +/- 2.2013, respectively) were markedly higher than those in HBeAg negative group (31.6%, 1.7863 +/- 0.6339, respectively, P<0.01). The detection rate of Pre-S1 Ag in these samples were 82% coincided with that of HBV DNA. The positive rate of Pre-S1 in the sera from five groups with different HB markers were well correlated to that of HBV DNA (r=0.9826, P<0.01). These results suggest that serum Pre-S1 detection can be used as a marker for the presence of the HBV genome and its quantitation will be correlated with the replication of virus.