Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are important events in the lives of patients with COPD. While several definitions exist for AECOPD, exacerbations that result in a hospitalization would nearly always be considered severe. On average, exacerbation rates are approximately 1 to 2 per patient-year with COPD hospitalizations averaging approximately 0.1 to 0.2 per patient-year. Many risk factors, some of which are modifiable, such as patient adherence to therapy, pulmonary rehabilitation, and type of medication used, influence the rate of AECOPD. Severe AECOPD that result in hospitalization often lead to several adverse affects, including decreased quality of life, diminished lung function, weakness, reexacerbations/rehospitalization, cardiopulmonary complications, and death. Preventing severe AECOPD and their sequelae is a critical component in treating our patients with COPD.