We determined the prevalence and incidence of hepatitis C virus (HCV) infection among hemodialysis patients and evaluate their risk factors. 80 patients on maintenance hemodialysis in Peking Union Medical College Hospital Dialysis Center from December 1994 to June 1995 were studied. 30 medical students were used as health controls. Serum samples were tested for HCV antibodies by a second-generation enzyme-linked immunosorbent assay (ELISA) and for HCV RNA using nested polymerase chain reaction (PCR) and retested for anti-HCV and HCV RNA three months later. 24 (30%) of 80 hemodialysis patients were anti-HCV positive, and 2 (3.6%) of 56 anti-HCV negative cases were found HCV RNA positive. By combined assessment, the HCV infection rate of hemodialysis patient was 32.5% (26/80). Mantel-Haenszel analysis showed that HCV infection was associated with multi-transfusions, dialysis over a long period, renal transplantation, history of operation. Samples of dialysate in 9 serum HCV RNA positive cases were directly detected for HCV RNA, and 3 were found HCV RNA detectable. HCV infection rate in hemodialysis patients is higher than that of general population. The main risk factors for HCV transmission is transfusion of unscreened blood but is not an independent factor, hemodialysis itself plays an important role, the length of time on dialysis, renal transplantation, blood-contaminated material and contaminated dialysis equipment are also the risk factors. Infected hemodialysis patients should be isolated.