BACKGROUND AND AIMS: The Hepatitis G virus (HGV) was recentl) recognized and the complete genome was sequenced. Even though the transmission of the virus through blood transfusion has been established the prevalence of HGV infection in the general population of Korea is unknown. This study was performed to assess the prevalence of HGV infection in volunteer blood donors whose donations were either accepted or rejected. METHODS: We tested 277 frozen serum samples that were collected at two red cross blood centers in Seoul and KyungGi-Do. Accepted donations were 142 samples and 135 samples were rejected due to B viral hepatitis, 48 samples, C viral hepatitis, 36 samples and high alanine aminotransaminase (ALT65 IU/L) 51 samples. HGV-RNA was identified in the serum by a reverse-transcription-polymeras-chain-reaction assay with nested primers deduced from a nonstructural region. RESULTS: HGV-RNA was detected in 1.4% of accepted donations (2/142) and 8.3% of C hepatitis positive samples (3/3A). But there was no HGV-RNA positive samples in hepatitis B and high Al.T groups. Five all HGV positive donors had a normal ALT level. Two accepted HGV positive blood was transfused to two recipients. One of two recipients became HGV positive without ALT elevation checked at 12 weeks later. CONCLUSIONS: HGV was present in the volunteer donor blood in Korea and transmitted by transfusion, even though posttransfusion hepatitis was not confirmed.