OBJECTIVE: To investigate signs of liver disease, and biochemical and immunological markers in blood donors with isolated GBV-C/HGV viremia. METHODS: Eighteen donors with isolated GBV-C/HGV viremia were followed up 3-5 years after initial identification. Testing for GBV-C/HGV RNA, GBV-C/HGV-E2 antibodies and a range of biochemical and immunological tests was performed. Thirteen donors consented to liver biopsy. RESULTS: Twelve donors remained GBV-C/HGV viremic at follow-up. Five donors had developed E2 antibodies. Liver biopsies revealed mild portal inflammatory lesions in 6/11 individuals with persistent viremia, and steatosis in 10/13 biopsied donors. CONCLUSION: Steatosis and mild portal inflammatory lesions were found in liver biopsies from several blood donors with isolated GBV-C/HGV viremia.