Introduction: Unified airway disease where upper respiratory tract inflammation including chronic rhinosinusitis (CRS) affects lower airway disease is known from asthma, bronchiectasis, cystic fibrosis and primary ciliary dyskinesia but little is known about CRS and health related quality of life in COPD. We investigate firstly, the prevalence of CRS in COPD. Secondly the impact of CRS on HRQoL. Thirdly, risk factors for CRS in COPD. Methods: cross-sectional study of CRS in 222 COPD patients from 2017 to 2019 according to EPOS2012/2020 and GOLD2019 criteria. Patients completed the COPD assessment test (CAT), Medical Research Council dyspnea scale and Sinonasal outcome test 22 (SNOT22) and questions on CRS symptoms. They then had a physical examination including flexible nasal endoscopy, CT-sinus scan and HRCT-thorax. Results: 22.5% of COPD patients had CRS and 82% of these were undiagnosed prior to the study. HRQoL (CAT, SNOT22 and the SNOT22-nasal symptom subscore) was significantly worse in COPD patients with CRS compared with those without CRS and healthy controls. Multiple logistic regression analysis suggests that the most likely candidate for having CRS was a male COPD patient who actively smoked, took inhaled steroids, had a high CAT and SNOT22_nasal symptom subscore. Discussion: the largest clinical study of CRS in COPD and the only study diagnosing CRS according to EPOS and GOLD. This study supports unified airway disease in COPD. The SNOT22_nasal symptoms subscore is recommended as a standard questionnaire for COPD patients and patients at risk should be referred to an otorhinolaryngologist.