Objective To analyze the regulatory T cell ( CD4 +CD25 +FoxP3 +T) levels in peripheral blood of patients with cavitary tuberculosis before and after surgery .Methods We compared the proportion of CD4 +CD25high T cells and CD4 +CD25 +FoxP3 +T cells in 13 patients with cavity tuberculosis pre-and post-operatively and in 10 healthy control subjects with flow cytometry .Results (1) The proportion of CD4 +CD25high T cells and CD4 +CD25 +FoxP3 +T cells were significantly higher in patients with cavity tuberculosis and at 1-month postoperatively than that in healthy controls(P<0.01).The proportion of CD4 +CD25high T cells and CD4 +CD25 +FoxP3 +T cells had no statistical significance between the patients with cavity tuberculosis at 6-months postoperatively and healthy controls (P>0.05).(2)The proportion of CD4 +CD25high T cells and CD4 +CD25 +FoxP3 +T cells decreased significantly af-ter 6 months surgery than preoperatively in patients with cavity tuberculosis (P<0.01).(3)Pre-and post-operative proportions of CD4 +CD25high T cells and CD4 +CD25 +FoxP3 +T cells showed a positive correlation ( r=0.878,P<0.01 ) .Conclusion The proportion of the circulating T regulatory cells increases in patients with cavity tuberculosis , and decreases after surgery .Infection with M.tuberculosis may induce regulatory T cell-surface molecular changes.