The authors examined the contribution of Hepatitis C Virus (HCV) to the morbidity of chronic liver diseases (CLD) in selected districts of Saga, Japan, one group with low (L) and the other with a high (H) mortality rate of CLD. Age and sex-matched epidemiological studies showed an extremely high morbidity of CLD in the H-district (5.3%) and a low one in the L-districts (2.1%). Randomized selected studies of anti-HCV antibodies showed an extremely high frequency of 10.8% in the H-district and a frequency of 4.6% in the L-district. In addition, the number of subjects with both CLD and positive anti-HCV antibodies was significantly higher in subjects older than the fifth decade, in the H-district. The high prevalence of HCV may be related to the high morbidity and mortality rate of CLD in these districts of Japan.