BACKGROUND: Olodaterol is a novel, inhaled long-acting β2-agonist (LABA) with >24-hour duration of action investigated in asthma and chronic obstructive pulmonary disease. METHODS: Two multicentre studies examined the efficacy and safety of 4 weeks' once-daily (QD) olodaterol (2, 5, 10 and 20 μg, with background inhaled corticosteroids) in patients with asthma. One randomised, double-blind, parallel-group study (1222.6; 296 patients) administered treatment in the morning. Pulmonary function tests (PFTs) were performed pre-dose (trough) and ≤3 hours post-dose (weeks 1 and 2), and ≤6 hours post-dose after 4 weeks; primary end point was trough forced expiratory volume in 1 second (FEV1) response (change from baseline mean FEV1) after 4 weeks. A second randomised, double-blind, placebo- and active-controlled (formoterol 12 μg twice-daily) incomplete-block crossover study (1222.27; 198 patients) administered QD treatments in the evening. PFTs were performed over a 24-hour dosing interval after 4 weeks; primary end point was FEV1 area under the curve from 0-24 hours (AUC0-24) response (change from study baseline [mean FEV1] after 4 weeks). RESULTS: Study 1222.6 showed a statistically significant increase in trough FEV1 response with olodaterol 20 μg (0.147 L; 95 % confidence interval [CI]: 0.059, 0.234; p = 0.001) versus placebo, with more limited efficacy and no evidence of dose response compared to placebo across the other olodaterol doses (2, 5 and 10 μg). Study 1222.27 demonstrated increases in FEV1 AUC0-24 responses at 4 weeks with all active treatments (p 24-hour duration of action. In patients with asthma, evidence of bronchodilator efficacy was demonstrated with statistically and clinically significant improvements in the primary end point of trough FEV1 response measured in clinics over placebo for the highest administered dose of 20 μg in Study 1222.6, and statistically and clinically significant improvements versus placebo in FEV1 AUC0-24 responses at 4 weeks for all doses tested in Study 1222.27, which also exhibited a dose response. Bronchodilator efficacy was seen over placebo for all olodaterol doses for morning and evening peak expiratory flow in both studies. All doses were well tolerated. TRIAL REGISTRATIONS: NCT00467740 (1222.6) and NCT01013753 (1222.27).