Background Tiotropium Respimat®, a once-daily long-acting anticholinergic agent, is effective as add-on to inhaled corticosteroids (ICS) ± a long-acting β2-agonist (LABA) in adults with symptomatic asthma. Safety and tolerability are key issues in the development of new therapies or established therapies in new disease areas. We present key safety data from five Phase III, randomised, double-blind, parallel-group trials that evaluated the efficacy and safety of once-daily tiotropium Respimat® versus placebo in adults with symptomatic asthma. Methods: Two 48-week trials of tiotropium Respimat® 5 µg (PrimoTinA-asthma®: NCT00776984, NCT00772538) in patients on high-dose ICS (≥800 µg budesonide or equivalent) + LABA; two 24-week trials of tiotropium Respimat® 5 µg and 2.5 µg (MezzoTinA-asthma®: NCT01172808, NCT01172821) in patients on moderate-dose ICS (400–800 µg budesonide or equivalent); one 12-week trial of tiotropium Respimat® 5 µg and 2.5 µg (GraziaTinA-asthma®: NCT01316380) in patients on low-dose ICS (200–400 µg budesonide or equivalent). All tiotropium doses were delivered via the Respimat® SoftMist™ inhaler. Results: 3476 patients were treated. Incidence of any adverse events (AEs), serious AEs and investigator-defined drug-related AEs was similar across treatment groups within each trial. AEs reported by ≥5% of patients were similar across all treatment groups within each trial (Table). The number of cardiovascular AEs was small in all five studies and comparable between tiotropium Respimat® and placebo. No deaths occurred in any trial. Conclusion: Once-daily tiotropium Respimat® is well tolerated and comparable with placebo in adult patients with symptomatic asthma receiving at least low- to high-dose ICS.