['Cystic fibrosis (CF) patients frequently suffer from chronic rhinosinusitis (CRS). The extent to which alterations in sinonasal innate immunity contribute to this disease process is unknown. Activation of sinonasal epithelial cell (SNEC) Toll-like receptors (TLRs),  an important component of the innate immune system, may be associated with the hyperinflammatory state observed in sinonasal mucosa of CF patients with CRS. This study compares expression of Toll-like receptor 9 (TLR9), in SNRCs collected from CF subjects with CRS to that of normal control  subjects.', 'This was a prospective study measuring TLR9 on SNECs collected via endoscopic-guided middle meatal brushings from 8 adult controls and 14 adult subjects with CF-associated CRS.', 'TLR9 expression was significantly elevated  in CF subjects at 91% ± 6% when compared with 76% ± 10% in normal controls (p = 0.001).'] Is sinonasal epithelial cell expression of Toll-like receptor 9 elevated in cystic fibrosis-associated chronic rhinosinusitis?