Background. With a few exceptions, most published studies do not show an influence of antibodies to the hepatitis C virus (HCV) on the success of a kidney transplant. Methods. We studied all our renal transplant recipients who had received kidneys from cadaver donors (n = 335) and had been treated with quadruple immunosuppression (steroids, azathioprine, and antilymphocyte antibodies, followed by cyclosporin). We had information on the status of the hepatitis C antibodies before and/or after the transplant in 320 cases (95.5%, in 300, pre-transplant). Patients with HCV antibodies before and/or after the transplant were considered to be HCV positive (HCV +). Results. The HCV + patients had more time in dialysis and a greater number of transfusions, hyperimmunized cases, and re-transplants. The evolution in the first post-transplant year was similar in both groups, but afterwards, the HCV + patients had proteinuria more often as well as worse kidney function. The survival rate of the graft was significantly less in the HCV + cases: 90.6, 68.3 and 51.0% at respectively 1, 5 and 10 years, compared with 91.5, 84.7 and 66.5% in HCV-patients (P < 0.01). The patient survival rate was: 96.4, 87.0, and 71.9% in the HCV + patients at 1, 5, and 10 years, compared with 98.2, 96.0 and 90.0% in the HCV- cases respectively (P < 0.01). The differences remained the same in stratified studies according to time spent in dialysis or pre/post-transplant evolution of HCV antibodies, even when immunologically highrisk patients were excluded. In multivariant analysis, the presence of HCV antibodies acted as a independent prognostic factor for the survival of the kidney and the patient: 3.0 (1.8-5.0) and 3.1 (1.2-7.8) odds-ratio (95% of the confidence interval), respectively. The main cause of death among HCV + patients was cardiovascular; there was no apparent increase in mortality rate due to infections or chronic liver disease. The loss of organs was mainly due to chronic nephropathy or death with a functioning kidney. Conclusion. The presence of hepatitis C antibodies, before or after transplantation, is associated with a worse long-term survival rate for both the patient and the transplanted kidney in our patients treated with quadruple therapy.