Molecular analysis through real time PCR showed that TLR9 expression was higher in IPF SLBs than in normal tissue; therefore to confirm these data and to localize the cellular source of pulmonary TLR9 mRNA expression, we performed immunohistochemistry on whole lung sections from IPF and normal margin surgical resection specimens. This evidence concerns the gene TLR9 and idiopathic pulmonary fibrosis.