BACKGROUND/AIMS: Serum HBV DNA levels are correlated with hepatic histologic activity in chronic HBV infection based on HBeAg. Liver injury may persist, even though HBV DNA are not detected by hybridization assay. This study was to investigate whether serum HBV DNA levels determined by more sensitive quantitative method are correlated with histologic activities in chronic HBV infections. METHODS: This study included 66 chronic HBV infected patients. HBV DNA level was quantified by Cobas Amplicor HBV Monitor(TM). RESULTS: Serum HBV DNA levels in HBeAg-positive patients were significantly higher than HBeAg-negative patients. In HBeAg-positive patients, serum HBV DNA levels showed a significant negative correlation with portal-periportal activity and fibrosis (r=-0.451, -0.446 respectively). AST levels were correlated with lobular, portal-periportal activity and fibrosis (r=0.432, 0.365, 0.301 respectively), whereas ALT levels were related to lobular activity (r=0.294). Elevated AST levels predicted lobular activity, portal-periportal activity, and fibrosis with moderate to severe degree (OR 1.733, 95% CI 1.083-2.775; OR 1.518, 95% 1.028-2.243, p=0.336; OR 17.897, 95% CI 1.517-211.208, p=0.022, respectively). CONCLUSIONS: In HBeAg-positive patients, serum HBV DNA level correlates inversely with histologic activity. On the other hands AST level correlates with histologic activity and the stage of moderate or severe degree.