8-Hydroxydeoxyguanosine (oh8dG) is a promutagenic DNA lesion produced by oxygen radicals. We examined alterations in the oh8dG level in human livers which have chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The oh8dG content in livers with chronic hepatitis was significantly higher than the oh8dG content in normal livers (P < 0.05). There was also a significant correlation between the oh8dG content in noncancerous liver tissues with individual serum alanine aminotransferase concentration (r = 0.515; P < 0.001). Thus, chronic inflammation in the liver produces oxidative DNA damage, which may increase the risk for genomic alterations causing hepatocarcinogenesis.