Abstract: Through the surveilance of humoral immune levels in 48 patients hospitalized with pulmonary tuberculosis under chemotherapy for 4-5 months, it was found that there are three different modes of humoral immune response among the patients after treatment. 66.6% of the patients showed a rising level of antimycobacterial antibodies in thire sera which reached the maxinum after 1-3 month treatment and then decreased slowly, 18.7% of the patients whose sera contained higher level of antimycobacterial antibodies at the beginning of treatment showed a slowly drop in the level of the antibodies after treatment; 14.6% of them whose sera contained low level of specific antibodies had no humoral immune response. The specific antibody levels in five patients during the surveilance period showed a periodic change. The results in the present paper showed that under the effect of chemotherapy the increased humoral immune response may play a protective role.