Hepatitis C (HC) has been recently diagnosed by determination of specific antibodies that represent the former so-called non-A, non-B hepatitis. We studied the prevalence of plasma HCV antibodies among 61 unselected patients on hemodialysis (HD) and 43 on continuous ambulatory peritoneal dialysis (CAPD). Plasma C-antibodies were determined through the ELISA test system. Transfusion policy was the same in both groups. The prevalence of hepatitis C virus antibodies was significantly higher in hemodialysis patients than among those on CAPD. Time on dialysis, previous blood transfusions, and renal transplantation seem to increase the prevalence of C hepatitis antibodies among hemodialysis patients. The effect of these parameters on CAPD was smaller. Understanding the reasons for these differences may help prevent this disease among dialysis patients.