The probability of developing hepatocellular carcinoma (HCC) among hepatitis C virus (HCV) carriers during their life-time is unknown. This paper addresses the estimation of the cumulative risk of HCC among HCV carriers using cross-sectional data. Age-specific prevalences of HCV carriers among the general population were estimated according to 5-year age group, based on the data of 2nd-generation anti-HCV assay in blood donors resident in Osaka (33,226 males and 29,054 females). Seropositivity of anti-HCV among 422 HCC cases, and the Osaka Cancer Registry data on HCC were used in the estimations of 5-year age-specific incidence rates of HCV-linked HCC. Using these data, the cumulative risk, i.e., the probability of contracting HCC within the following 15 years in 50-year-old HCV carriers, was estimated as 28% for males and 6% for females.