Both animal and human studies have demonstrated the adoptive transfer of immunity against hepatitis B virus (HBV) through liver transplantation that may be attributed to the presence of HBV-specific immunocompetent cells of donor origin in liver grafts. In this study, we characterized the resident lymphocytes in 41 human liver grafts by immunohistochemical staining and flow cytometry and directly identified the intragraft HBV-specific lymphocytes in relation to the donor's and subsequent recipient's immunity using enzyme-linked immunospot assay. A significant number of HBV-specific T and B cells were detectable in 59.4% (19/32) and 28.1% (9/32), respectively, of liver grafts from HBV-immune donors. The presence of various HBV-specific lymphocytes was closely associated with each other and with a higher serum titer of antibody against hepatitis B surface antigen (anti-HBs) in donors (P Ͻ 0.05). After liver transplantation, 17 of 35 (48.6%) patients with chronic HBV infection showed a spontaneous anti-HBs production, which was significantly associated with a higher number of donor-derived T lymphocytes specific for hepatitis B surface antigen (P ϭ 0.043). In conclusion, the presence of considerable numbers of donor-derived HBV-specific immunocompetent cells in grafts may account for the adoptive transfer of HBV immunity through liver transplantation.