Background. The development of hepatocellular carcinoma (HCC) is associated closely with cirrhosis. In the present study, the cumulative risk of HCC in patients with cirrhosis was investigated.Methods. A total of 401 patients were registered from April 1977 and followed for a mean of 4.4 years. Of 401 patients, 255 (64%) were tested for hepatitis B surface antigen (HBsAg) and antibody (anti-) to the hepatitis C virus (HCV); 87 (34%) patients were positive for HBsAg but were negative for anti-HCV (hepatitis B virus [HBV] group), 126 (49%) were negative for HBsAg but were positive for anti-HCV (HCV group), 10 (4%) were positive for both and 32 (13%) were negative for both (non-B non-C group)Results. By the end of March 1993, HCC was diagnosed in 127 (31.6%) patients. The cumulative risk of HCC in the HCV group was slightly higher than that in HBV group (P = 0.3, 5-year risk: 36.9 versus 21.2%). In contrast, the rate was significantly lower in the non-B non-C group than in the HBV or HCV groups (P < 0.05 and P < 0.01, respectively, 5 year risk: 12.4%).Conclusions. These results suggest that not only HBV infection but also HCV infection increase the risk for HCC in patients with cirrhosis.