Abstract: Objective To observe the present duration of the anti TB-IgG in the serum in cured tuberculosis patients.Methods The anti TB-IgG in the serum in cured tuberculosis patients had been tested by ELISA in which PPD acts as the coated antigen every three months for 18 months.Results The number of positive patients decreased gradully.The decreasing rate was the greatest from 109 patients in the 9th month (63.0%) to 21 patients in the 12th month (12.1%).The number of positive patients in the 12th month was much more than that of healthy control (P< 0.05).The number of positive patients in the 15th month was 11(6.4%) and no significant difference from the health control (P> 0.05).Conclusion The present duration of anti TB-IgG in the cured pulmonary tuberculosis patients was about 12 months to 15 months.On the chronic fibrotic caritary tuberculosis patients,before the treatment its focus scope was wide,after cured,the present duration of the patients with the proliferativeform as the major focus was longer.

Key words: ELISA, Tuberculosis,pulmonary, Anti TB IgG