A study of a cross-section of the Hong Kong Chinese population was done to investigate the seroprevalence of hepatitis C. Healthy subjects were random visitors of a health exhibition, while clinical subjects were recruited from an outpatient liver disease clinic, sexually transmitted disease clinics, dialysis centres and drug rehabilitation centres. A total of 910 subjects were tested. The assay kits were from Abbott and Ortho laboratories. Of the general population, 0.5% was found to be positive for antibody to hepatitis C (anti-HCV). Suspected chronic non-A non-B patients, parenteral drug abusers and haemophiliacs shared a common high (up to 70%) prevalence of anti-HCV. Sexual partners of index patients, homosexuals and female prostitutes as well as hepatitis B carriers had 0% prevalence. It was concluded that parenteral and blood product exposures were the two main risk factors for hepatitis C.