Groups in the Western countries have been well studying CTL recognition of hepatitis C using HCV-epitopes presented by HLA-A*0201 most frequently seen in Caucasians. We, on the other hand, identified HCV-epitopes presented by HLA-B*3501 (J. Gen. Virol. 79: 1735-1744, 1998). With a tetramer using these epitopes, we directly analyzed HCV-specific CD8 T cells in the peripheral blood from patients with acute and chronic hepatitis C. The result confirmed that in the early phase of acute hepatitis, there was higher frequency of HCV-specific CD8 T cell compared to chronic hepatitis, as was seen in HBV patients. It also revealed that HCV-specific CD8 T cells observed in the early phase of acute hepatitis were primarily those of memory phase (Hepatology. 33: 287-294, 2001).