Asthma is a chronic inflammatory airway disease, and its treatment is frequently challenging despite detailed national and international guidelines. While basic anti-inflammatory therapy usually consists of inhaled corticosteroids in doses adapted to the asthma severity, add-on treatment with bronchodilators is essential in more severe asthma. Only recently, the long-acting anticholinergic tiotropium was introduced into the GINA guidelines. This review reports on the studies that have been performed with tiotropium in adult asthmatic patients. Following early proof-of-concept studies, several studies with tiotropium as an add-on therapy to inhaled corticosteroids (ICS), with or without a long-acting beta agonist (LABA), demonstrated convincing clinical benefit for patients. Important lung function parameters and quality of life scores significantly improved shortly after onset of the add-on therapy with tiotropium, and some studies even demonstrated non-inferiority against salmeterol. All studies reported an excellent safety profile of tiotropium. The still growing body of tiotropium studies, both in adults and children, will help to identify the position of tiotropium in future asthma guidelines and might also indicate which patients benefit most from an add-on therapy with tiotropium.