Culture supernatant harvested from Daudi cells, a lymphoplastoid cell line, after 58 days of infection with the H77 strain of hepatitis C virus (HCV), was inoculated into a chimpanzee. HCV RNA, as detected by RT-PCR, first appeared in the serum and liver 5 and 6 weeks, respectively, after inoculation. Peripheral blood mononuclear cells (PBMC) collected on week 7 were also positive for HCV RNA. The major sequences of hypervariable region 1 (HVR1) of the viral genome recovered from the inoculated chimpanzee were the ones which were the majority in the original H77 inoculum and not those which were in the majority in the culture supernatant. Only the sequence recovered from PBMC was the same as the major one found in the cell culture.