Antibody response in HCV infection may be variable and the variability of the serological response could be due to the differences in HCV strains. Since the distribution of hepatitis C virus genotype has been found to be geographically dependent, it is important to determine the distribution of HCV genotype in various countries with high prevalence of chronic non-A, non-B hepatitis. In this study, serum HCV RNA was examined in 53 patients suspected of chronic non-A, non-B hepatitis with an anti-HCV test as determined by currently available assay. HCV viremia was detected in 48 patients (90.6%). These patients had elevated serum ALT level at the time of HCV RNA determination. Using specific genotype probes, all isolates were classified into three different genotypes. Double and triple infections were also noted. HCV genotype 1b is the predominant genotype found in chronic hepatitis C patients in Jakarta.