Abstract: Objective To investigate the duration of TB antibody positive in patients treated formally as pulmonary tuber culosis and provide evidence for seroepidemiological survey on pulmonary tuberculosis and epidemic situation of TB.Methods In 15 months,the TB antibody in patients treated as pulmonary tuber culosis were detected every 3 months using rapid test TB diagnostic kit(MyCoDot TM)produced by Dyna Gen corporation,and compared with normal health examination group.Results 190 cases were implemented whole range observation in 260 patients.Positive cases descended every 3 months,and the descent of ninth month was most obvious.There was no significant difference between the patients and the normal(χ²=2.4391,P>0.05).The duration of the TB antibody positive between different ages and types in pulmonary tuber culosis patients was distinct and the difference was significant.Conclusion The duration of the TB antibody positive in patients treated formally as pulmonary tuberculosis was about 9~12 months.The duration of the TB antibo dy positive in patients extensive focus prior treatment and proliferating focus post treatment was longer.The positive TB antibody short term after treated couldn't be considered as clinical evidence of active TB.If the TB antibody showed positive reaction 9~12 months after treatment,the possibility of relapse tuberculosis should be considered.