A morphologic comparison between hepatitis C virus-related cirrhosis (HCV cirrhosis) and hepatitis B virus-related cirrhosis (HBV cirrhosis) was performed. The materials consisted of 37 surgical specimens obtained from patients with hepatocellular carcinoma (HCC) positive for antibodies to HCV (anti-HCV) and negative for HBV serologic markers, and 21 specimens from patients positive only for hepatitis B surface antigen (HBsAg). In addition, the evolution of the type of cirrhosis associated with HCC was studied in 43 autopsy cases from 1970 to 1975 and 44 cases from 1989 to 1994. The histological features of HCV cirrhosis are characterized by broadly expanded fibrous septa, small regenerative nodules, and a relatively strong inflammatory reaction with prominent lymphoid aggregation and mild regenerative activity of the hepatocytes. HBV cirrhosis is characterized by larger regenerative nodules, a weak inflammatory reaction, and marked regenerative activity of the hepatocytes. In a comparison of the types of cirrhosis associated with HCC during the six-year period from 1970 to 1975 with the six-year period from 1989 to 1994 at Kurume University School of Medicine, macronodular cirrhosis (which was mostly HBsAg-positive) declined from 38.8% to 13.6%; by 1989-1994, most of the associated cirrhosis was mixed macronodular and micronodular type with anti-HCV in serum (in 84%). The morphologic type of cirrhosis associated with HCC reflected the proportion of viral hepatitis due to HBV or HCV involved.