We examined the relationship between HBV-DNA isolated from the liver and from the serum in patients with various serological characteristics of chronic hepatitis B infection. Amplification and direct sequencing of the HBV pre-core/core region was carried out in 9 patients who were seropositive for HBsAg and HBV-DNA--4 HBeAg positive and 5 anti-HBe positive. Complete sequence identity was observed between HBV-DNA isolated from the serum and the liver in individual patients. In addition, shortened forms of the HBV core ORF were detected in patients with chronic active hepatitis, but not in patients with chronic persistent hepatitis.