Background: The safety of long-acting β2 agonist (LABA) therapy in asthma remains controversial but no large scale analyses have been published of LABA safety in children. Methods: The frequency of asthma-related deaths and hospitalisations following formoterol use in children (4-11 years) and adolescents (12-17 years), compared with non-LABA treatment, was assessed in all AstraZeneca-sponsored, randomised, controlled, parallel-group trials (≥3 months) where formoterol was used as maintenance and/or as reliever therapy. Results: 11 849 children and adolescents under the age of 18 years from 41 trials were identified, 82% of whom used an inhaled corticosteroid (ICS) as concomitant medication. The number of asthma-related deaths (one 13-year-old boy among 7796 formoterol-treated patients, and none among 4053 non-LABA-treated patients) was too low to allow any between-group comparison. The frequency of patients with asthma-related hospitalisations was not different in formoterol-treated versus non-LABA-treated patients, either in children (1.16% (38/3263) vs 1.11% (24/2165)) or in adolescents (0.51% (23/4533) vs 0.85% (16/1888)). Asthma-related hospitalisations based on daily dose of formoterol were: (A) 4.5 or 9 μg: 1.9% (18/980); (B) 18 μg: 0.5% (14/2870); (C) 36 μg: 0% (0/67); and (D) variable dosing: 0.75% (29/3879). There was no difference between formoterol-treated and non-LABA-treated patients as regards ethnicity. Conclusions: Formoterol use in children and adolescents (4-17 years) with asthma in this large study where the majority are prescribed concomitant ICS is not associated with any increased risk of asthma-related hospitalisations. The results are not influenced by dose or ethnicity.