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Background: Host genetic factors may play a role in the susceptibility to active tuberculosis (TB), and several polymorphisms in different cytokine coding genes have been described and associated with diseases to date. Objectives: To investigate whether polymorphisms within the promoter region of the TNF-α (-238/-308) coding genes are associated to the occurrence of active TB. Methods: SNPs within the TNF-α gene were analyzed by PCR-RFLP among two groups of individuals: patients with TB (n = 234, and patients non TB (n = 113). Results: In this study, the presence of the-238A allele was associated with susceptibility to TB disease occurrence and severity (p = 0,00002; OR = 0,15; IC = 0,06-0,36. On the contrary, the-308A allele was associated with protection to the occurrence of another pulmonary diseases. Conclusions: These results suggest the importance of genetics studies on TB occurrence. Further studies are needed pursuing a better understanding of the human pathogenesis of M. tb. Key words: uberculosis/genetics. Polymorphism, single nucleotide/genetics. Tumor necrosis factor/genetics. Alleles. Genotype