Hypersensitivity pneumonitis (HP) is an interstitial lung disease that develops after inhalation of a variety antigens in susceptible individuals. The nasal mucosa is constantly exposed to these antigens that can irritate the respiratory mucosa. So, the purpose of this study was to study nasal histopathological changes in order to identify any shared pathological changes between the upper airways and the well-known pathological features of HP. 40 HP patients diagnosed at the Chest Department, Kasr Alainy hospital following ATS/JRS/ALAT guidelines were included. Patients were subjected to thorough history, high-resolution computed tomography, spirometry, cough evaluation test (CET), sinonasal outcome test-22 (SNOT-22), sinonasal examination and nasal mucosal biopsy by an otolaryngologist under visualization by a rigid nasal endoscope. The mean age of the patients was 46.2 ± 13.5 (85% were females and 15% were males). 90% of patients presented with cough and the mean CET was 17.15 ± 5.59.77.5% of patients suffered from sinonasal symptoms and the mean SNOT-22 was 12.18 ± 3.8. There was a significant correlation between the burden of sinonasal symptoms represented by the SNOT-22 and the severity of the cough represented by CET (r 0.40, p 0.01). 87.5% of HP patients had chronic inflammation of the nasal mucosa with predominant lymphocytic infiltration in 72.5% of patients. 77.5% of HP patients had a high burden of sinonasal symptoms which is positively associated with cough severity. 72.5% of patients had predominately lymphocytic infiltration of the nasal mucosa.Trial registration: retrospectively registered, registration number is NCT05723796, date of registration 13/02/2023.