The performance of a commercially available assay for detection of hepatitis C virus (HCV) antibody in saliva samples was assessed. Samples of saliva were collected from 270 individuals whose HCV antibody status was determined by serum assay (161 HCV-positive, 109 HCV-negative). The saliva samples were tested for the presence of HCV antibodies using a modified protocol. The sensitivity was 94.4% (95% CI, 89.3-97.2%) and the specificity 99.1% (95% CI, 94.3-100%). Although the optical density in tests on HIV-positive individuals was lower than that among HIV-negative individuals, the HIV status had no significant influence on the results of the HCV assay in saliva. These findings suggest that tests on saliva can be useful in epidemiological studies for estimating the prevalence of HCV in populations that are difficult to reach.