Abstract: Objective To evaluate the therapeutic effect of Mycobacterium vaccae（M.vaccae）vaccine on tuberculosis pleurisy.Methods Eighty cases of tuberculosis pleurisy were divided randomly into study group（40 cases） and control group（40 cases）.All of the two groups were treated by chemotherapy with a regimen of 2HALZ/6HL₂ and aspirating pleural effusion.And the study group was given intramuscular injections of M.vaccae vaccine once weekly for three months,the control group took prednisone for 6～8 weeks.Results The rates of pleural thickening were 5% in the study group and 22.5% in the control group.There was significant difference（P＜0.05）.The average times of absorption of pleural effusion were 19.3 days in the study group and 28.3 days in the control group.There was significant difference（P＜0.01）.The relapse rates following 1.5 years follow-up were 0 in the study group and 8.6% in the control group（P＞0.05）.The side effects of M.vaccae vaccine were local in duration（1 case） and slight fever（1 case）,Conclusion M.vaccae vaccine is an effective and safe drug to reduce pleural thickening in treating patients with tuberculous pleurisy.

Key words: Mycobacterium vaccae vaccine, Tuberculosis,pleura/drug therapy