Background and purpose: Bronchiectasis revealed by high-resolution computed tomography (HRCT) is common in chronic obstructive pulmonary disease (COPD), but the causes and risk factors remain to be determined. Chronic rhinosinusitis (CRS) is closely associated with bronchiectasis or COPD, but whether it is associated with comorbid bronchiectasis in COPD (COPD-Bx) is unknown. Patients and methods: Patients with stable COPD were enrolled consecutively and - evaluated for the presence of CRS by questionnaire and paranasal sinus computed tomography. The presence and severity of bronchiectasis on lung HRCT were evaluated by the Smith and severity scores. COPD symptoms were evaluated by COPD Assessment Test (CAT) and Modified British Medical Research Council Questionnaire. The sputum cell differentials and concentrations of interleukin (IL)-6, IL-8, IL-5, matrix metalloproteinases-9 (MMP-9), and tissue inhibitor of matrix metalloproteinases-1 were measured. Results: We enrolled 136 patients with stable COPD, of which 66 (48.5%) were diagnosed with CRS according to the European Position Paper on Rhinosinusitis and Nasal Polyps (EP3OS) criteria. The prevalence of bronchiectasis was 57.6% in patients with CRS, but 37.1% in those without CRS (P=0.017). COPD-Bx patients with CRS showed a significantly higher severity score of bronchiectasis than those without CRS (P=0.034). COPD patients with CRS had a higher percentage of eosinophils, higher levels of IL-8, IL-6, and MMP-9 in sputum as compared to those without CRS. In COPD-Bx patients with CRS, the percentage of eosinophils and the levels of IL-6 and MMP-9 in sputum were increased as compared to those without CRS. In all the subjects, Sino-Nasal Outcome Test-20 correlated with CAT score (r=0.315, P<0.01) and in COPD patients with CRS, Lund-MacKay scores correlated with forced expiratory volume in 1 s (% pred) (r=-0.251, P<0.05). Conclusions: CRS was associated with COPD-Bx and this was probably due to increased airway inflammation.