Since the last meta-analysis in 1989, a number of randomised trials on the benefit of glucocorticoids have been published, resulting in an increasing interest in the use of glucocorticoids to treat outpatients with croup. The objective of this review was to provide evidence to guide clinicians in their treatment of patients with croup, to examine the effectiveness of glucocorticoids in these patients, and to identify areas of uncertainty for future research.To determine the effect of glucocorticoids for children with croup.We searched The Cochrane Controlled Trials Register, MEDLINE (January 1966 to August 1997) and Excerpta Medica/EMBASE (January 1974 to August 1997). We also contacted (by mail) authors of identified croup trials published in the last five years to inquire about other trials, published or unpublished.Meta-analysis of randomised controlled trials that examine the effectiveness of glucocorticoid treatment in children with croup.Data were extracted using a structured form, which captured patient status (inpatient or outpatient), intervention and control, with the name of the drug, route of administration and dose. Data were also collected on the primary outcome measures comprised of a clinical croup score at baseline (as well as any other subsequent assessment times), length of stay (hours), patients status improved (yes/no), and use of co-interventions. The quality of the trials was assessed using empirically derived items that involved scales and components. Two researchers (TPK, MA) then selected studies as being potentially relevant based on a review of the titles and abstracts, if available. The complete text of these studies was then retrieved. All studies that had been retrieved were reviewed independently by two reviewers (AS, TPK). Data were extracted by one reviewer (MA) and checked for accuracy by a second reviewer (TPK). Two observers independently assessed quality (MA, JK), and inter rater agreement was measured by the intra class correlation. Differences were resolved by consensus.Twenty-four studies were deemed relevant for inclusion (N=2221). Glucocorticoid treatment was associated with an improvement in the croup severity score at 6 hours with an effect size of -1.0 (95% confidence interval -1.5 to -0.6) and at 12 hours -1.0 (-1.6 to -0. 4); at 24 hours this improvement was no longer significant (-1.0, -2. 0 to 0.1). There was a decrease in the number of adrenaline treatments needed in children treated with glucocorticoids: a decrease of 9% (95% confidence interval 2 to 16%) among those treated with budesonide and of 12% (4 to 20%) among those treated with dexamethasone. There was also a decrease in the length of time spent in accident and emergency (-11 hours, 95% confidence interval -18 to 4 hours), and for inpatients hospital stay was reduced by 16 hours (-31 to 1 hour). Publication bias seems to play a part in these results.Dexamethasone and budesonide are effective in relieving the symptoms of croup as early as 6 hours after treatment. Fewer co-interventions are used and the length of time spent in hospital is decreased in patients treated with glucocorticoids.