Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a common presentation to emergency departments (ED) but data regarding its epidemiology and outcomes are scarce. We describe the epidemiology, clinical features, treatment and outcome of patients treated for AECOPD in ED.This was a planned sub-study of patients with an ED diagnosis of AECOPD identified in the Asia, Australia and New Zealand Dyspnoea in Emergency Departments (AANZDEM) study. The AANZDEM was a prospective, interrupted time series cohort study conducted in 46 ED in Australia, New Zealand, Singapore, Hong Kong and Malaysia over three 72-h periods in May, August and October 2014. Primary outcomes were patient epidemiology, clinical features, treatment and outcomes (hospital length of stay (LOS) and mortality).Forty-six ED participated. There were 415 patients with an ED primary diagnosis of AECOPD (13.6% of the overall cohort; 95% CI: 12.5–14.9%). Median age was 73 years, 60% males and 65% arrived by ambulance. Ninety-one percent had an existing COPD diagnosis. Eighty percent of patients received inhaled bronchodilators, 66% received systemic corticosteroids and 57% of those with pH < 7.30 were treated with non-invasive ventilation (NIV). Seventy-eight percent of patients were admitted to hospital, 7% to an intensive care unit. In-hospital mortality was 4% and median LOS was 4 days (95% CI: 2–7).Patients treated in ED for AECOPD commonly arrive by ambulance, have a high admission rate and significant in-hospital mortality. Compliance with evidence-based treatments in ED is suboptimal affording an opportunity to improve care and potentially outcomes.