Exacerbations of chronic obstructive pulmonary disease (COPD) play a very important role. Unfortunately they were neglected a long time in the therapeutic tests. However exacerbations influence the decline of the respiratory function over time, cause important deterioration of the quality of life of the patients, increase morbidity and mortality of COPD, and finally represent a burden for health care. Reducing the number of exacerbations could potentially slow down the progression of the disease. Thus the prevention of exacerbations should be the "corner stone" of the maintenance treatment of the COPD. In this review we propose to recall the importance of exacerbations in COPD and to present the treatment which have been shown to reduce exacerbation rate in COPD.