Antibody to hepatitis C virus (anti-HCV) was measured by enzyme-linked immunosorbent assay (ELISA) in 167 intravenous drug addicts, 10 oral drug addicts, 49 patients without liver disease and 58 blood donors. It was found that the prevalent rate of anti-HCV in these groups were 92.2%, 10%, 2.0% and 1.7%, respectively. It is also noted that the prevalence of anti-HCV for intravenous drug addicts was significantly higher than that for oral drug addicts, patients without liver disease, and blood donors (P < 0.001). There was no significant difference among the later three groups. It is indicated that intravenous drug addicts are high-risk group of HCV infection. Injecting drug with injectors of HCV carrier, injectors and/or solvent not being sterilized may contribute to prevalence of HCV in these groups. It is similar that the distributions of HCV infection in intravenous drug addicts with different trait.