The aim of the study was to examine the state of hepatitis B virus (HBV) DNA in liver tissue of 103 children with chronic hepatitis B aged 0.5-18 years to detect free and integrated viral sequences by Southern blot hybridization. HBV DNA was found in 74 patients. Seventy-two were seropositive for hepatitis B e antigen (HBeAg) and two had anti-HBe antibodies. Integrated sequences could be demonstrated in two children. One of them had only integrated HBV DNA and was anti-HBe seropositive. The other one presented both free and integrated viral sequences and developed seroconversion from HBeAg to anti-HBe 5 months after biopsy. In 29 hepatitis B surface antigen (HBsAg) carriers, no HBV DNA could be detected in the liver. Ten were HBeAg and 19 anti-HBe seropositive. HBV DNA in serum was found in 65 of the 74 Southern blot-positive and only in two cases of the Southern blot-negative patients. In conclusion, most of the HBeAg-positive children had free HBV DNA in their liver tissue and all patients with anti-HBe except one were negative. According to our results, HBV DNA integration into the liver cell genome can occur at an early stage of chronic disease but is not a frequent event.