Abstract: Objective To determine the incidence,clinic epidemiological characteristics and the roles of Mycobacterium tuberculosis L forms infection in the diffusion and metastasis of lung carcinoma.Methods One hundred and two cases of formalin fixed and paraff in embeded tissue samples of surgically resected lung carcinomas were confirmed fur ther by his topathological observation with hematoxy lineosin(HE)staining.With MPB64 probe,the target gene and its location in the tissue samples were detected with in situ hybridization technique.Mean while the Mycobacterium tuberculosis L forms in the sample was detected with inten sified Kiny ouns acid fast staining.Results MPB64 gene fragment was detected in 83 of 102 lung cancinoma paraffin embeded tissue(81.4%).To tally 67 Myobacterium taberculosis L forms positive cases were found in 102 lung cancinoma tissues(67.6%).There sults of the two methods had no-significant difference(P>0.05).Conclusion The incidence of Mycobacterium tuberculosis L forms infection in lung carcinoma suggests that the infection is likely to be involved in the occurrence or development of lung carcinoma.