Stored sera is available from people who have attended the Hepatitis and HIV clinics at the Alfred Hospital. Sera is available back to approximately 1990 and has been stored at minus 20ºC and as such is suitable for GBV-C detection particularly RNA by PCR. Of the sera stored by the HIV clinic 203 patients are known to be co-infected with HCV who are currently still alive. Once ethics committee approval is obtained we propose to contact these groups of people and see if they would participate in this study. Once consent is obtained we plan to perform the following.