Abstract: Objective: To detect the changes of the number of NK cells and intracellular killing molecules in peripheral blood of patients with pulmonary tuberculosis. Methods: Percentages of NK cells in peripheral whole blood samples from 145 pulmonary TB patients(105 first-treated pulmonary TB and 40 retreated pulmonary TB) and 112 healthy controls were collected, labelled with anti- CD3,CD56,CD8, granulysin,perforin and granzyme antibody, and analyzed by flow cytometry. Results: The percentage of NK cells in first-treated pulmonary TB patients was(16. 95 8. 27) %,which was significantly lower than that in healthy controls(19. 99 9. 28) % (P ＜ 0. 01 ) . Absolute value of NK cells in first-treated pulmonary TB patients was (33. 31 21. 44 ) 104 /ml,which was significantly lower than that in healthy controls (44. 32 26. 69) 104 /ml) (P ＜ 0. 05) . Absolute value of NK cells in retreated pulmonary TB patients was (36. 8 24. 97) 104 /ml. Granulysin［(85. 78 11. 63) % vs (87. 31 10. 34) %］,perforin［(82. 88 17. 05) % vs (82. 85 13. 03) %］in NK cells had no difference bewteen pulmonary TB patients and healthy controls(P ＞ 0. 05) ,but the difference of granzyme［(79. 07 15. 64) % vs (88. 04 7. 27) %］was significant(P ＜ 0. 01) . Conclusions: The number of NK cells in peripheral whole blood of first-treated pulmonary TB patients NK was significantly decreased. However, the expressions of granulysin and perforin in NK cells had no difference between pulmonary TB patients and healthy controls.