Objective: To evaluate TGF-beta(1) expression in polypoid mucosa (epithelium and stroma) of patients with chronic rhinosinusitis with nasal polyposis (CRSwNP).Methods: Cross-sectional study with two groups: 17 patients with nasal polyposis and 11 controls. Polyps and normal nasal mucosa were processed by immunohistochemical methods for TGF-beta 1 visualization. Then, the percentage of TGF-beta 1 expression in stroma and epithelium was objectively quantified using UT Morph software.Results: A lower percentage of positive expression was found in the epithelium of CRSwNP patients (32.44%) versus normal controls (55.91%) (p < 0.05), and a higher percentage of positive expression in the stroma of CRSwNP patients (23.24%) versus controls (5.88%) (p < 0.05).Conclusion: the lower percentage of TGF-beta(1) expression in the nasal epithelium of CRSwNP patients may have an impact on epithelium-directed topical treatments employed in this patient population.Universidade Federal de São Paulo, Dept Otolaryngol Head & Neck Surg, São Paulo, BrazilUniv Ghent, Ghent Univ Hosp, Dept Otorhinolaryngol, Upper Airway Res Lab, B-9000 Ghent, BelgiumUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Otolaryngol Head & Neck Surg, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, São Paulo, BrazilWeb of Scienc