The course of COPD is punctuated by acute exacerbations that are associated with an increase in the morbidity and mortality related to this chronic disease and may contribute to its rate of progression. Therefore, preventing and treating exacerbations are major goals of COPD management. The role of tiotropium in the prevention of exacerbations has been investigated in several placebo-controlled randomized clinical trials varying in duration from 3 months to 4 years in patients with moderate to very severe COPD. In all of these trials, tiotropium has uniformly reduced the proportion of patients experiencing at least one exacerbation and delayed the time to the first exacerbation compared with placebo. In the longer trials (≥6 months’ duration) tiotropium has also reduced the exposure-adjusted incidence rate of exacerbations. In trials of at least 1 year in duration, tiotropium either significantly reduced the risk of hospitalization for an exacerbation and/or the proportion of patients with an exacerbation-related hospitalization. In a meta-analysis that included 15 trials of tiotropium vs either placebo (n = 13) and/or a long-acting beta-agonist (LABA; n = 4), tiotropium significantly reduced the odds of experiencing an exacerbation compared to placebo as well as a LABA. The potential additive benefits of tiotropium to those of a LABA and/or inhaled corticosteroid in reducing exacerbations require further investigation. The mechanism whereby tiotropium reduces exacerbations is not due to an anti-inflammatory effect but more likely relates to its property of causing a sustained increase in airway patency and reduction in hyperinflation, thereby counteracting the tendency for respiratory insults to worsen airflow obstruction and hyperinflation. For the management of acute exacerbations, an increase in short-acting inhaled bronchodilators is recommended as needed, while the potential role of long-acting bronchodilators, such as tiotropium, in conjunction with short-acting agents, is unclear and warrants further study.