We studied whether chronic hemodialysis is associated with an increased risk of exposure to hepatitis C virus. Utilizing a first generation Elisa assay (C-100 Elisa, Ortho Diagnostic Systems, Raritan, NJ) and the Chiron RIBA HCV second generation assay (RIBA, Chiron, Emeryville, CA and Ortho Diagnostic Systems, Raritan, NJ), antibody to HCV was found in 31 of 87 hemodialysis patients (36%). Patients on hemodialysis less than 2 years had an antibody incidence of 15% (n = 46), as contrasted with a 59% incidence for patients on dialysis greater than or equal to 2 years (n = 41). We were unable to demonstrate a correlation of HCV-antibody positivity with history of blood transfusion. The overall incidence is higher than previously reported for hemodialysis patients in the United States. The very high incidence found in patients on dialysis greater than or equal to 2 years suggests that factors in the hemodialysis unit might contribute to the spread of virus.