Anticholinergic agents have important uses as bronchodilators for the treatment of obstructive airway diseases, both asthma and, more particularly, chronic obstructive pulmonary disease (COPD). Those in approved clinical use are synthetic quaternary ammonium congeners of atropine, and include ipratropium bromide, oxitropium bromide, and tiotropium bromide, each of which is very poorly absorbed when given by inhalation. Ipratropium and oxitropium have relatively short durations of action (4-8 h). They have been widely used for many years, either alone or in combination with short-acting beta-adrenergic agents such as albuterol and fenoterol, for both maintenance treatment of stable disease and for acute exacerbations of airway obstruction. Tiotropium, which was introduced in the early 2000s, has a duration of action of at least 1-2 days making it suitable for once-daily maintenance treatment of COPD. All of the above agents have a wide therapeutic margin and are safe and well tolerated by patients.