Background: Asthma and chronic obstructive pulmonary disease (COPD) are the most common obstructive diseases. Based on the similarities, we aimed to evaluate sinonasal symptoms in patients with asthma or COPD, and compare the two diseases with regard to upper-airway involvement. Methods: Patients with asthma or with COPD who were followed up at Ankara University Immunology and Allergy or Chest Diseases Departments were included in the study. The participants went through pulmonary function tests, skin-prick tests, and disease severity assessment of either disease. Nasal endoscopic evaluations of all the patients were performed in the Department of Otorhinolaryngology. Lund-Mackay scoring was performed on the computed tomography of the paranasal sinus. Chronic rinosinusitis (CRS) diagnosis was made as recent guidelines. Results: A total of 112 subjects (number of women/men: n = 67/45; median age, 49 years [The range for IQR was 22 years]) were included in the study. Fifty-five patients had asthma, 33 had COPD, and 24 were healthy controls. Nasal symptoms were more frequent in the patients with asthma (patients with asthma, n = 52 [98%]; patients with COPD, n = 17 [52%]; controls, n = 9 [38%]) (p < 0.001). The median (IQR) 22-item Sino-Nasal Outcome Test (SNOT-22) questionnaire score was higher in the patients with asthma (33 [20-50]) than in the patients with COPD (8 [1.5-18.7]) and the control group (3.5 [0-18.7]) (p < 0.01). Patients with asthma had significantly higher prevalence rates of rhinosinusitis than did those in the COPD and the control groups (36%, 15.6%, 8.3%, respectively; p < 0.01). The SNOT-22 optimal cutoff score was calculated as ≥11 to detect the score limit for CRS prediction with the best sensitivity and specificity. Conclusion: As a result, patients with both asthma and COPD may have upper-airway symptoms. CRS, was primarily seen in the patients with asthma. Accordingly, SNOT-22 scores were higher in the patients with asthma than in those in the COPD and the control groups. A referral to the Ear Nose Throat department for further evaluation with nasal endoscopy and computed tomography of the paranasal may be required in a subgroup of patients.