The HBeAg was detected in 5 of 24 patients with acute type B hepatitis (20.8%), 33 of 95 with chronic hepatitis (34.7%), 6 of 33 with liver cirrhosis (18.2%), and 3 of 39 with hepatocellular carcinoma (7.7%). On the other hand, anti-HBe was found in 4.2% of acute hepatitis, 18.9% of chronic hepatitis, 9.1% of liver cirrhosis, and 12.8% of hepatocellular carcinoma. We found that an early detection of HBeAg in patients with acute hepatitis is of no prognostic value, but its persistence may provide the earliest evidence of potential chronicity. In chronic liver diseases, HBeAg-positive cases showed remarkable fluctuations of serum transaminase levels, severe histological changes and poor responses to treatment. Many of the HBeAg-positive patients lost their initial positivity of HBeAg within six months or one year and in some cases serocoverted to anti-HBe after acute exacerbation. Follow-up study more than several years revealed that the presence of anti-HBe reflect an inactive stage and a more favorable outcome, whereas persistence of HBeAg may provide an active and continuing hepatocellular damage. From these results, we believed that serial measurements of HBeAg/anti-HBe system are useful prognostic marker in patients with HBsAg-positive liver disease.