Croup is an acute clinical syndrome of childhood characterised by a barking cough, hoarse voice, stridor and a variable degree of respiratory distress. A meta-analysis and subsequent controlled trials clearly demonstrate that corticosteroids are efficacious in the management of croup, with their benefits conclusively outweighing their risks. In mild to moderate cases of croup either systemic or nebulised corticosteroids decrease symptoms and need for hospitalisation. Most reports use IM dexamethasone 0.6 mg/kg, although it is likely that dexamethasone 0.15 mg/kg has a similar effect. In controlled studies nebulised budesonide 2 mg is superior to placebo, and appears to have equivalent efficacy to oral dexamethasone. The risk of a single or short course of systemic corticosteroids are minimal, the only potential significant adverse effect being increased risk of severe varicella infection. Short courses of nebulised budesonide have no major adverse effects, and thus are likely to cause fewer adverse effects than systemic corticosteroids, although this is as yet unproven. On the body of data published to date, either oral dexamethasone 0.15 mg/kg or nebulised budesonide 2 mg are effective for mild to moderate croup. In severe croup requiring intubation, oral prednisolone 1 mg/kg every 12 hours decreases the duration of intubation and the need for re intubation. Unless there are clear contraindications, corticosteroids are the treatment of choice in mild, moderate and severe croup.