Abstract: Objective To explore the reason of delayed diagnosis or misdiagnosis of pulmonary tuberculosis. Method The clinical data of 458 patients pulmonary tuberculosis patients undergoing treatment between January 1999 and December 2003 in our hospital were retrospectively analysed. Results and Conclusion The reasons for delayed diagnosis or misdiagnosis are as follows: A careless attitude towards health condition by patients themselves; neglected bacteriological evidence or ignorance of tuberculosis by physicians.