A study was made of 73 samples from 6 chronic hepatitis B patients, 2 out of the 6 cases were non-treated and the 4 cases were interferon treated HBeAg, HBeAb, s-ALT and HBV-DNA. Detection of HBeAg and HBeAb were assayed by AxSYM system (Dainabot), which were based on microparticle enzyme immunoassay. 1) Fifty-three out of 73 samples showed positive for HBeAg; 45 samples showed only HBeAg positive (Group A) and 8 samples showed HBeAg and HBeAb positive (Group B). The positive ratios of HBV-DNA in each group 91.1% (41/45) and 50.0% (4/8), respectively and 4 out of the rest 20 samples that showed only HBeAb positive also showed HBV-DNA positive. The above 12 discrepant samples between HBeAg and HBV-DNA were collected from 4 chronic hepatitis B patients who became normal s-ALT levels after liver injury. The HBeAg S/N ratio (sample/negative control) of these samples were near the cutoff value (S/N = 2.1). 2) Comparing the movement between HBeAg and s-ALT levels in 6 chronic hepatitis B patients, the changes of HBeAg S/N ratio were related with the changes of s-ALT. The changes of HBeAg S/N ratio were observed before the movement of s-ALT. In conclusion, the detection of HBeAg/HBeAb by AxSYM system was useful to monitor the clinical course of chronic hepatitis B patients.