AIM: Recent studies in Iran has shown that prevalence of hepatitis C virus (HCV) infection among Iranian prisoners is high, in spite of low HCV seroprevalence in general population.METHODS: This study was carried out in the central prison of Hamedan - Iran, in year 2002. Inmates were interviewed using a standard questionnaire including demographic,imprisonment history and HCV-related risk behaviors items. Thereafter, the sera drawn from the participants were tested for anti-HIV and anti-HCV antibodies.RESULTS: A total number of 427 drug abuser inmates participated in our study. Three hundred and ninety-seven (93%) were men and 30 (7%) were women. Total number of Ⅳ drug abusers (IDA) and non-Ⅳ drug abusers (NIDA)was 149 (34.9%) and 278 (65.1%), respectively. The overall rate of antibody positivity among inmates was 0.9% for HIV and 30% for HCV. Of all IDAs, 31.5% and of NIDAs, 29.1% had serological evidence of HCV infection.CONCLUSION: The seroprevalence of HCV infection among drug abuser prisoners in comparison with the general population in Iran, is very high (30% vs in italics 0.2%).Our results indicate the importance of policies to prevent transmission of HCV infection during and following incarceration.