Dupilumab is a monoclonal antibody which blocks the IL-4 receptor and inhibits signalling by IL-4 and IL-13, type 2 inflammatory cytokines released in childhood asthma. Dupilumab has efficacy in asthma, atopic dermatitis and allergic rhinitis in adults. In this double-blind randomised controlled trial, 408 children aged 6–11 years with uncontrolled moderate-to-severe asthma received a subcutaneous injection of dupilumab or placebo every 2 weeks, in addition to their standard background therapy.1 The primary endpoint, the annualised rate of severe asthma exacerbations, was 0.31 (95% confidence interval 0.22–0.42) with dupilumab and 0.75 (95% confidence interval 0.54–1.03) with placebo, relative risk reduction 59.3%, P < 0.001. The mean (±SE) change from baseline in the percentage of predicted bronchodilator forced expiratory volume in 1 s (ppFEV1) was 10.5 (±1.0) percentage points with dupilumab and 5.3 (±1.4) with placebo (P < 0.001). The frequencies of adverse events during the 52-week trial period were similar across trial groups in the safety population (83.0% with dupilumab and 79.9% with placebo) with no major safety signal. Eosinophilia, which occurred more commonly with dupilumab (5.9%) than placebo (0.7%), was mostly asymptomatic and self-limited. However, a single child with eosinophilia had associated clinical symptoms which required hospitalisation and permanent discontinuation of dupilumab.