Tuberculosis is a chronic mycobacterial infection. The main effector cells against mycobacterium tuberculosis are CD4+ T lymphocytes. Our objective in this research was to evaluate the quantity of T lymphocytes and their subpopulations before and after treatments with combination of 4 drugs (Rifampcin, Isoniaside, pyrasinamide, Ethambutal) for 2 months directly in sputum-positive tuberculosis patients. Twenty patients as cases and twenty healthy people were selected as controls. Flow cytometry was used for TCD3+, TCD4+ and TCD8+ lymphocytes by using monoclonal antibodies. Our results indicated that there was alteration in cell mediated immunity during tuberculosis showing itself as decrease in TCD3+ and TCD4+ lymphocytes and increase in TCD8+ lymphocytes. The changes in TCD3+ and TCD4+ but not in TCD8+ were reversible after 2 months of treatment.