The aim of the present work is to evaluate the commercially available antibody tests in the diagnosis of hepatitis C virus (HCV) infection by comparing their results with the RT-PCR test. The study included 316 serum samples from three groups: blood donors, patients on maintenance hemodialysis (HD) and patients infected with the human immunodeficiency virus (HIV). Samples were subjected to HCV-antibody detection by ELISA and RIBA tests and HCV-RNA detection by RT-PCR assay. The percentage of infectivity for blood donors was 18.9% by ELISA, 20.8% by RIBA and 23.6% by RT-PCR test. For patients on HD and those positive for HIV, the test positivity was respectively 59.3% and 5.3% by ELISA, 64% and 10.5% by RIBA and, 66.3% and 21% by PCR test. The percentage of false negativity of HCV-Ab by ELISA and RIBA when compared with RT-PCR test was 3.5 and 8.1% for samples blood donors, 17.1 and 25.7% for HD patients and 5.6 and 16.7% for HIV-infected samples, respectively. The false positivity of HCV-Ab by ELISA and RIBA, when compared with RT-PCR, was 5%, 3.9% and zero for blood donors, HD patients and HIV-HCV co-infected cases, respectively. While comparing ELISA with RT-PCR, the false positivity was 10%, 5.9% and zero respectively for blood donors, HD patients and HIV-HCV co-infected cases. Thus, it is very important to screen blood donors, HD patients and HIV-infected patients by using the RT-PCR for HCV-RNA to avoid false negative results.