Non-A, non-B hepatitis is a significant cause of liver disease among renal allograft recipients. In order to assess the impact and prevalence of hepatitis C in a series of renal allograft recipients, we retrospectively screened 621 consecutive patients transplanted between 1979 and 1989 and 484 cadaver organ donors retrieved in the same interval for serologic evidence of hepatitis C viral (HCV) infection using the enzyme-linked assay for anti-HCV antibody. Of 596 HBsAg negative patients, 180 (30%) were anti-HCV positive at the time of transplant. One-year posttransplant, 117 (22%) had detectable levels of anti-HCV antibody. Chemically significant hepatitis developed in 52/234 (22%) anti-HCV positive patients, and 26 of these followed a clinical course consistent with chronic hepatitis. Significantly more males and patients with antibody to HCV detectable at 1 year posttransplant were in the group experiencing an increase in liver enzymes. Ten-year patient and graft survival was 78% and 50%, respectively, for the anti-HCV positive patients who had an elevation of alanine aminotransferase, and 76% and 57% for the cohort maintaining normal liver function (P = NS). There were also no differences in patient and graft survival among the anti-HCV positive group and the consistently sero-negative patients. Of 484 cadaver organ donors with serum available for analysis (out of 1200 retrieved), 67 (14%) were anti-HCV positive at the time of organ donation. Among 23 anti-HCV negative kidney recipients who received a kidney from an HCV antibody positive donor, only one had seroconverted at 1 year posttransplant. Antibody to HCV appears to be widespread among renal transplant recipients and cadaver organ donors. We were unable to demonstrate any evidence of long-term adverse effects on patient and graft survival among anti-HCV positive patients employing the first generation anti-HCV assay.