The prevalence of anti-HCV in patients after kidney transplantation was tested by HCV-Antibody-ELISA (Ortho Diagnostics). In addition, reactive samples were tested by HCV-EIA (Abbott Laboratories), neutralization, anti-HBc (Corzyme, Abbott) and by HBs-Ag (Auszyme, Abbott). 27 of 271 patients (10%) were anti-HCV positive. Receiving more than one kidney graft (TPL) or the transfusion of more than four blood units (BU) increases the risk of HCV infection four times (OR: 4.1; p less than 0.01) or 2.5 times (OR: 2.5; p less than 0.05), respectively, compared with one TPL or less than 4 BU. Receiving more than one kidney graft and transfusion of more than four BU raises the risk of HCV infection 6.8 times. 52% of anti-HCV positive patients were anti-HBc positive, 48% were anti-HBc negative as well as HBs-Ag negative.