Recently, an RNA virus member of the flaviviridae, GBVirus C(GBV-C) was isolated from the serum of patient with cryptogenic hepatitis, but clinical significance for this virus has been not known now. To estimate the prevalence of GBV-C, we investigated the presence of GBV-C RNA by reverse transcription-nested polymerase chain reaction in the serum from various liver disease patients. The results were summarized as follows: [Table: see text] Among these, only 5 patients gave positive results, and these 5 cases had the history of blood transfusion before. Especially both non B non C HCC patient and non A non B non C fulminant hepatitis patient were negative for GBV-C on admission, while positive after blood transfusion as treatment. In the non B non C HCC patient, GBV-C RNA persisted over a period of several months after transfusion, while no remarkable elevation of ALT was observed. These results demonstrated that GBV-C/HGV may be transfusion-transmissible, and may not associated with severe chronic liver disease such as liver cirrhosis or HCC.