There have been few prospective studies of hepatitis C virus (HCV) infection after needlestick accidents in hospital employees. In the present study, the prevalence and features of HCV infection after needlestick accidents were evaluated prospectively measuring serum HCV-RNA. Subjects were 56 employees who had HCV needlestick accidents. To monitor the development of hepatitis, the serum ALT levels and HCV-related seromarkers, such as first generation anti-HCV (RIA), second generation anti-HCV (PHA) and HCV-RNA (RT-PCR) were measured every month for at least 12 months after the accidents. Three of 56 (5.4%) recipients developed HCV infection. HCV-RNA was detected in all three recipients within 4 months after the exposure, and second-generation HCV antibody was detected in two of three recipients. The detection of HCV-RNA was earlier than that of HCV antibody. Two of three HCV-infected recipients developed type C acute hepatitis and one of two received interferon therapy; however, the other case received no medication. The detection of HCV-related seromarkers and the elevation of ALT levels were transient in these three recipients: thus, none developed chronic hepatitis. In conclusion, HCV infection developed in 5.4% of recipients within 4 months after HCV accidents. All of these HCV-infected recipients showed fair prognosis. HCV-RNA was a beneficial parameter for early detection of HCV infection.