4‐Hydroxy‐2‐nonenal (HNE) is one of the major components of lipid peroxidation product and has been shown to react with proteins to form HNE‐protein adducts. HNE‐protein adducts are relatively stable and can be used as a marker of radical‐mediated cellular damage. We report herein the immunohistochemical analysis of HNE‐protein adducts in human alcoholic liver diseases using a specific monoclonal antibody HNEJ‐2. Cytoplasm of hepatocytes and bile duct epithelia was positively stained for HNE‐protein adducts, and the nucleus was negligibly stained. The immunohistochemical intensity of hepatocytes was classified into three groups: strong, moderate, and faint staining. Strong staining was found in 43% of alcoholic liver diseases and in 4% of viral liver diseases. Hepatocytes of alcoholic liver diseases contained a higher amount of HNE‐protein adducts than those of viral liver diseases, and the difference was statistically significant (p = 0.005; χ² test). Semiquantitative analysis of the histological intensities of HNE‐protein adducts and iron indicated a significant positive correlation (p = 0.084; Spearman's rank correlation). The localization of HNE‐protein adducts and iron in hepatocytes appeared to be identical. These data suggested the correlation between HNE‐protein adducts and iron. Our results indicate that HNE‐protein adducts, a marker of oxidative stress‐induced damage, are increased in human alcoholic liver damage, and that hepatic siderosis may act on the production of free radicals.