In an attempt to evaluate the prevalence, the kinetics and the impact of HCV infection in renal transplantation, we analyzed 140 kidney recipients according to hepatic histology: 33 HBsAg negative patients had chronic active hepatitis, 73 HBsAg negative patients had a normal liver, 21 HBsAg negative kidney recipients had minimal pathological changes and 13 patients had HBsAg positive cirrhosis. Serum antibodies to HCV were detected using the ELISA test. The overall prevalence of anti-HCV antibodies was 24.3 percent: anti-HCV were more frequently present in HBsAg negative patients with chronic active hepatitis (57.5 percent) than in HBsAg negative patients with normal liver (8.2 percent) (P less than 0.0001) or minimal changes (33.3 percent, NS) and HBsAg positive patients with cirrhosis (15.4 percent) (P = 0.02). Among the 30 anti-HCV positive kidney recipients with serological follow up, 13 (43.3 percent) had anti-HCV antibodies at the time of transplantation and kept anti-HCV during follow up, 11 (36.7 percent) acquired anti-HCV after renal transplantation in a mean time-lag of 95 months while 6 (20 percent), who had anti-HCV prior to transplantation, exhibited negativation of anti-HCV antibodies in a mean time-lag of 111 months after transplantation. The kinetics of anti-HCV antibodies was the same irrespective of the liver status. Patients and grafts survivals were not different in anti-HCV positive and anti-HCV negative kidney recipients, whatever the hepatic histology. Our data suggest that, in kidney transplantation, a) the prevalence of anti-HCV antibodies is around 24 percent in kidney recipients and varies greatly according to hepatic histology; b) anti-HCV antibodies are not systematically associated with the development of chronic liver disease; c) post-transfusion hepatitis as well as so called community acquired hepatitis may occur in transplantation follow up; d) HCV infection does not clearly influence the survival of allograft or that of kidney recipients.