Once thought to be a mere nuisance, exacerbations are now recognized as a major contributor to the morbidity and mortality associated with chronic obstructive pulmonary disease. This recognition has led to research using new investigative tools that has substantially enhanced our understanding of the pathogenesis of exacerbations. Several overlapping etiologies can precipitate the symptom complex of an exacerbation. Treatment of exacerbations requires the use of several therapeutic modalities with the goal of restoring the patient to baseline. Results of recent clinical trials and observational studies have allowed a refinement of the approach to treatment of exacerbations. These include a rational, stratified approach to the use of antibiotics and several trials substantiating the use of systemic corticosteroids. Relapse or failure rates of 20 to 33% have been described in the treatment of acute exacerbation, with these treatment failures contributing substantially to the costs associated with exacerbations. Improved treatment based on enhanced understanding and good clinical evidence should lead to better outcomes in this common clinical entity.