To assess the frequency of hepatitis C virus antibodies (anti HCV) and exposure to hepatitis B virus in injectable and oral drug users in Auckland. Sera from 110 injectable drug users and 154 oral drug users were tested for anti HCV as well as hepatitis B and D virus markers. Liver function tests were also performed. 73% of injectable drug using persons and 4% of oral drug using persons were positive for anti HCV. Over half of persons with a positive anti HCV result had an abnormal elevation of the liver enzyme alanine aminotransferase (ALT). Total HBV exposure was similar in both injectable drug user and oral drug user groups at approximately 30%, with little difference between ethnic groups. There were no positive results for hepatitis D virus infection. Injectable drug users who are anti HCV positive may represent a potential source of HCV infection in the community. An upgraded educational programme, perhaps in conjunction with the needle/syringe exchange programme, may be required to ensure drug users are aware of the risks of HCV infection to both themselves and the community.