The significance of apoptosis in liver injury or liver fibrosis in viral hepatitis is yet unknown. The authors investigated the hepatocyte apoptosis and the correlation between the apoptosis and the liver injury in 22 liver biopsy specimens from the patients with hepatitis. Specimens were put onto slides to detect DNA strand breaks in situ with nick end labeling method using terminal deoxynucleotide transferase and bio-11-dUTP (TUNEL). The results showed that most of TUNEL-positive hepatocytes which have the features of apoptosis were apoptotic hepatocytes. There was TUNEL-positive reaction in few of the hepatocytes with ballooning degeneration. The degree of apoptotic hepatocytes in the chronic hepatitis was stronger than that in the acute hepatitis. This suggested that the degree of apoptotic hepatocytes correlated with the chronicity of hepatitis.