BACKGROUND: The changes of the composition in the T-lymphocyte are important as an immunological abnormality in the pathogenesis of tuberculosis. Previously, the second type of TCR dimer(gamma delta T lymphocyte) that did not express CD4 or CD8 molecules was found. In other reports the presence of this type of lymphocytes was increased in the initial stage of tuberculous infections. METHOD: To determine whether there are some differences in the T-lymphocyte subsets in the peripheral blood or pleural effusion among the forty-nine patients were examined T-lymphocyte subset analysis(CD4+T-cell,CD8+ T-cell,gamma delta T-lymphocytes) with anti-Leu4, anti-Leu3a, anti-Leu2a, anti HLA-DR and anti-TCR-gammadelta-1(Becton