Mirabegron, a β(3)-adrenoceptor agonist, has been developed for the treatment of overactive bladder (OAB).To assess the efficacy and tolerability of mirabegron versus placebo.Multicenter randomised double-blind, parallel-group placebo- and tolterodine-controlled phase 3 trial conducted in 27 countries in Europe and Australia in patients ≥ 18 yr of age with symptoms of OAB for ≥ 3 mo.After a 2-wk single-blind placebo run-in period, patients were randomised to receive placebo, mirabegron 50mg, mirabegron 100mg, or tolterodine extended release 4 mg orally once daily for 12 wk.Patients completed a micturition diary and quality-of-life (QoL) assessments.