Hepatitis C virus (HCV) is one of the perilous problems in hemodialysis (HD) centers around the world. There are many risk factors regarding HCV infection in HD units. The aim of this study was to evaluate the incidence of HCV infection in HD units and also to assess the potential risk factors in this regard. A total of 334 patients on regular HD were evaluated. All the patients were seronegative for anti-HCV antibody in the beginning of this study. They were followed every 6 months with repetition of tests. Positive samples were tested by polymerase chain reaction (PCR) for confirmation. The prevalence of HCV infection was about 20%. No significant relationship between numbers of blood transfusion, age and sex was obtained. A positive correlation between HCV infection and duration of HD for more than 5 years was significant. In conclusion, our study found the prevalence of HCV infection to be significantly higher than its incidence in the general population.