['To assess the effectiveness of nurse-initiated administration of oral corticosteroids before physician assessment in moderate to severe acute asthma exacerbations in the pediatric ED.', 'A time-series controlled trial evaluated nurse initiation of treatment with steroids before physician assessment in children with Pediatric Respiratory Assessment Measure score ≥4. One-to-one periods (physician-initiated and nurse-initiated) were analyzed from September 2009 through May 2010. In both phases, triage nurses initiated bronchodilator therapy before physician assessment, per Pediatric Respiratory Assessment Measure score. We reviewed charts of 644 consecutive children aged 2 to 17 years for the following outcomes: admission rate; times to clinical improvement, steroid receipt, mild status, and discharge; and rate of return ED visit and subsequent admission.', 'Nurse-initiated phase children improved earlier compared to physician-initiated phase (median difference: 24 minutes; 95% confidence interval [CI]: 1-50; P = .04). Admission was less likely if children received steroids at triage (odds ratio = 0.56; 95% CI: 0.36-0.87). Efficiency gains were made in time to steroid receipt (median difference: 44 minutes; 95% CI: 39-50; P < .001), time to mild status (median difference: 51 minutes; 95% CI: 17-84; P = .04), and time to discharge (median difference: 44 minutes; 95% CI: 17-68; P = .02). No differences were found in return visit rate or subsequent admission.'] Is triage nurse initiation of corticosteroids in pediatric asthma associated with improved emergency department efficiency?