BACKGROUND Although remodeling changes of the lower airway are well described, similar changes in the upper airway are less well known. Remodeling changes of the upper airway in chronic rhinosinusitis (CRS) relevant to different phenotypes and endotypes and their clinical characteristics are investigated. METHODS A cross-sectional study of adult patients with CRS was performed. Mucosal samples were taken during endoscopic sinus surgery (ESS). Histopathological analysis included eosinophil count, eosinophil activation (eosinophilic mucin), and remodeling changes. Mucosal damage was defined as ulceration, edema, and hypertrophic changes. Patient-reported outcomes (PROMs) were assessed using a Nasal Symptom Score (NSS) and Sino-Nasal Outcome Test (SNOT-22). Patients were subgrouped by presence of polyps (CRSwNP/CRSsNP) or tissue eosinophilia (>10/high power field). Subgroup analysis was performed when both eosinophilic chronic rhinosinusitis (eCRS) and eosinophil activation (eCRSwEA) were coexistent. Analysis between subgroups, pathology, and PROMs was also performed. RESULTS A total of 259 patients (age 48.5 ± 15.6 years, 45% female) were recruited; 53% CRSwNP, 51% eCRS. Remodeling changes were present in 85%, higher in both CRSwNP (90%, p = 0.006) and eCRS (91%, p = 0.004). Mucosal damage changes were common in eCRS (ulceration 18%, p = 0.003; edema 98%, p < 0.001; hypertrophic changes 25%, p = 0.007). NSS was worse in CRSwNP compared to CRSsNP (2.84 ± 1.1 vs 2.29 ± 1.1, p < 0.001) and eCRSwEA (2.95 ± 0.16 vs 2.51 ± 0.11, p = 0.04). "Loss of sense of smell or taste" was worse in patients with evidence of mucosal damage (p = 0.006). CONCLUSION Remodeling features are present in CRS. Tissue eosinophilia and evidence of eosinophil activation is closely associated with remodeling features of CRS, associated mucosal damage and clinical symptoms.