Background: Extra domain A-containing fibronectin (EDA-FN) is necessary for the development of allergen-induced lower airway fibrosis. The pathogenesis of fibrosis in allergic rhinitis has not been well studied. Objectives: To determine whether EDA-fibronectin is necessary for the development of nasal remodeling in a murine model of chronic allergic rhinitis and in human allergic rhinitis. Methods: EDA(-/-) and wild-type (WT) C57Bl/6 mice were sensitized intraperitoneally and then challenged with inhaled ovalbumin (OVA) or saline for 2 and 5 weeks. Clinical signs of rhinitis and histological analysis of nasal tissue were evaluated. Immunohistological staining for EDA-FN was performed in human tissue of inferior nasal conchae from patients with allergic rhinitis and controls. Results: After 2 weeks of allergen exposure, only goblet cell hyperplasia and perivascular eosinophilia were observed. After 5 weeks, goblet cell number, thickening of the subepithelial layer, and extent and area of collagen deposition were increased in the nasal tissue of WT OVA (ovalbumin)-challenged mice as compared with saline controls (P <.0001, P <.0001, P =.018, and P =.03, respectively). Clinical signs of rhinitis were observed only in WT OVA-challenged mice. In the EDA(-/-) mice exposed to OVA, collagen deposition, collagen area, and subepithelial thickness showed no increase and were similar to saline control mice, whereas goblet cell hyperplasia was similar to WT OVA-challenged mice. EDA-FN expression was prominent in inferior conchae from patients with allergic rhinitis but was absent in control patients. Conclusion: EDA-containing fibronectin is necessary for the development of nasal tissue fibrotic remodeling process in both murine and human allergic rhinitis.