Acute exacerbations of COPD (AECOPD) are a common cause of morbidity and mortality. There is a need for a standardised definition of an exacerbation of COPD. The common aetiological factors are bacterial, viral infection and air pollutants. Exacerbations of COPD may adversely affect the natural history of COPD. Several strategies are available now to prevent or reduce exacerbations of COPD including immunisation against influenza and inhaled corticosteroids in patients with moderate/severe disease. The mainstay of treatment involves increasing bronchodilator therapy, systemic glucocorticoids which have now been shown to have a beneficial effect. The circumstances for the use of antibiotic therapy is now established in patients with increased breathlessness, increased sputum production and/or sputum purulence. In those with respiratory failure, noninvasive ventilation has been shown to reduce intubation rates, shorten lengths of hospitalisation, and improve mortality. Early or immediate supported discharge for selected patients has been shown to be effective in the management of patients with COPD.