In our study, we investigated the association between TLR9 rs5743836 T1237C SNP and the risk of COPD and its exacerbation, where we found that the TLR9 rs5743836 mutant (C/C) genotype and the C allele were expressed in higher frequency in COPD patients and in the exacerbated group compared with control and stable groups, respectively. Here, TLR9 is linked to chronic obstructive pulmonary disease.