Aim: Asthma is a major contributor to direct and indirect health-care costs and resource use. In May 2015, the Royal Children's Hospital (RCH) amended its clinical practice guideline for acute asthma management from discharging patients if the anticipated salbutamol requirement was every 3-4 h to discharging patients who were clinically well at 1 h after initial treatment. Our objective was to examine the impact of the new discharge recommendation on emergency department (ED) length of stay (LOS), rates of admission and representation. Methods: We retrospectively audited the case notes of children presenting with mild or moderate asthma to the RCH ED over the equivalent 2-week periods in winter 2014 (pre-implementation of the new guideline) and 2015 (post-implementation).Results: A total of 105 patients in 2014 and 92 patients in 2015 were included. In both years, all patients who initially presented with mild or moderate asthma either improved or stayed within the same severity classification at the 1-h assessment. For patients who were clinically well by the 1-h assessment, there was a significant reduction in admissions between 2014 and 2015 (40 vs. 10%, P = 0.001). There was also a reduction for these patients in median LOS from 3 h 13 min in 2014 to 2 h 31 min in 2015 (P = 0.03). In both years, all patients who were moderate at 1 h were admitted. There was no difference in the rate of representation or subsequent deterioration in those patients who were discharged at 1 h between the 2 years.Conclusion: Early discharge of patients who are clinically well 1 h after initial therapy may be associated with a reduction in LOS and admission rate without an apparent compromise in patient safety. Further evaluation of this intervention is required to determine whether this is a true causal relationship.