T lymphocytes have been reported to be the predominant inflammatory cells in the liver of patients with chronic viral hepatitis. Their presence may reflect either nonspecific inflammation or a virus-specific immune response. To assess the repertoire of intra-hepatic T cells, we investigated the TCR V beta gene usage of T cells in 10 patients with chronic hepatitis B and 15 with chronic hepatitis C. Liver-derived lymphocytes and peripheral blood lymphocytes were analyzed by flow cytometry. Five out of the 10 hepatitis B patients were found to have an accumulation of certain V beta T cells in the liver (V beta 6.7; V beta 6.7; V beta 3.1, V beta 5.1, and V beta 6.7; V beta 3.1; V beta 12.1, respectively). Four out of the 15 hepatitis C patients were found to have an accumulation of certain V beta T cells in the liver (V beta 5.1; V beta 8 and V beta 5.2 and 5.3; V beta 3.1 and V beta 5.2 and 5.3; V beta 3.1 and V beta 12.1, respectively). Despite a limited screening of V beta subfamilies, this study indicates that, in patients with chronic hepatitis B and C, T cells using a certain V beta gene may accumulate in the liver. This suggests that intra-hepatic T cells are oligoclonal and possibly virus specific. Our results argue against the role of a superantigen in perpetuating liver disease. In addition, this study supports a role for T lymphocytes in the pathogenesis of chronic hepatitis C.