During a 16-month period in 1991-1992, blood samples and questionnaire data were obtained from 65 incident cases of hepatocellular carcinoma (HCC) as well as from 2 control groups of hospitalized patients matched on gender and age, which included 65 metastatic liver cancer (MLC) patients and 65 patients hospitalized for eye, ear, nose or throat conditions. Coded sera were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen, antibody to HBsAg and antibody to hepatitis C virus (anti-HCV) by enzyme immunoassay. The odds ratios (with 95% confidence intervals) in logistic regression modeling comparing the HCC cases to the combined control series were 18.8 (8.2-43.2) for the presence of HBsAg and 7.7 (1.7-35.1) for anti-HCV. In the present hospital-based case-control study anti-HCV testing was conducted on recently collected sera, using a second-generation enzyme immunoassay with confirmation by immunoblot assay. Comparisons with previous work in a similar population demonstrated that, when second-generation anti-HCV assays are applied to sera stored for 7-15 years, confirmatory assays or a higher diagnostic cut-off point may be necessary to ensure that the testing is specific.