Apoptosis is a type of cell death which is clearly distinguishable from necrosis in its morphological and biochemical features. To clarify the role of apoptosis in alcoholic liver injury, we investigated the expression of apoptosis-related Lewis(Le)(y) antigen by immunohistochemistry in liver samples from patients suffering from alcoholic liver disease. Liver biopsy samples were taken from 20 patients who drank more than 80 g of ethanol per day on average. Indirect immunohistochemical staining was carried out using anti-cytokeratin and anti-Le(y) antibodies. To examine the relationship between Mallory bodies and apoptosis, double staining was performed using both antibodies. In alcoholic hepatitis, many Mallory bodies were stained with anti-cytokeratin antibody in hepatocytes of the centrilobular area. Le(y) antigen was also detected in hepatocytes in the same area. Immunohistochemical double staining showed that some of the hepatocytes containing Mallory bodies were stained with anti-Le(y) antibody. Few hepatocytes expressing Le(y) antigens, however, were observed in other types of alcoholic liver disease, including steatosis, fibrosis and cirrhosis. From these results, it is suggested that apoptosis may also be involved in alcoholic hepatitis and that hepatocytes containing Mallory bodies can be eliminated by apoptosis.