The prevalence of antibodies to hepatitis C virus (anti-HCV) was determined in 105 patients with biopsy-proven chronic liver disease and 128 comparison patients without any evidence of liver pathology living in Lima, Peru. Using a second-generation EIA screening and supplemental immunoblot assay, anti-HCV was detected in four of 13 patients with chronic hepatitis, in 11% of 85 patients with cirrhosis, and in none of seven patients with hepatocellular carcinoma. Only two (1.6%) comparison patients without liver disease had anti-HCV. Hepatitis B surface antigen (HBsAg) was found in 23% of patients with chronic hepatitis, 12% of patients with cirrhosis, and three of seven patients with hepatocellular carcinoma. There was no evidence of chronic viral hepatitis or alcohol abuse (reported by one-third of subjects) in 48% of chronic liver disease patients. These preliminary data suggest that among this South American population neither hepatitis B nor hepatitis C infection is the predominate cause of chronic liver disease and that other infectious or environmental factors may be important. © 1994 Wiley-Liss, Inc.