Objective:To gain an insight into the immunological mechanism of tuberculosis by observing the variation of T lymphocyte subgroups in endobronchial tuberculosis(EBTB) patients.Methods:The variation of T lymphocyte subgroups was determined by flow cytometry in 23 EBTB patients and 25 physical examinees and results were compared.Results:The value of CD8 T lymphocytes was significantly lower in the EBTB patients than in healthy controls(P0.05).Conclusion:The pathogenesis of tuberculosis is associated with the changes in the immune system.CD4 and CD8 T lymphocytes play an important role in the cell-mediated immune response.