BACKGROUND: Duchenne muscular dystrophy is the most common muscular dystrophy of childhood. This incurable disease is characterised by muscle wasting and loss of walking ability leading to complete wheelchair dependence by 13 years of age. Prolongation of walking is one of the major aims of treatment. OBJECTIVES: The aim of this review was to assess whether glucocorticoid corticosteroids stabilize or improve muscle strength and walking in boys with DMD. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group specialised register (October 2003) using the term 'Duchenne muscular dystrophy'. We also searched MEDLINE (January 1966 to October 2003), EMBASE (January 1980 to October 2003), CINAHL and LILACS (January 1982 to October 2003). We wrote to authors of published studies and other experts in this disease to help identify other trials, checked the references in the identified trials and handsearched the abstracts of relevant journals. SELECTION CRITERIA: Types of studies: randomised or quasi-randomised trials.Types of participants: all patients with a definite diagnosis of Duchenne muscular dystrophy.Types of interventions: glucocorticoids such as prednisone, prednisolone, deflazacort or others, with a minimum treatment period of three months.Primary outcome measure: prolongation of walking (independent walking without long leg calipers).Secondary outcome measures: strength outcome measures, manual muscle strength testing using Medical Research Council strength scores, functional outcome measures and adverse events. DATA COLLECTION AND ANALYSIS: We identified five randomised controlled trials that met the inclusion criteria for our review. Two reviewers independently selected the trials for the review and assessed methodological quality. Data extraction and inputting were double-checked. MAIN RESULTS: Primary outcome measure: data from one small study used prolongation of walking as an outcome measure and did not show significant benefit.Secondary outcome measures: The meta-analysis of the results from three randomised controlled trials showed that glucocorticoid corticosteroids improved muscle strength and function over six months. Improvements were seen in time taken to rise from the floor (Gowers' time), nine metres walking time, four-stair climbing time, ability to lift weights, leg function grade and forced vital capacity. One randomised controlled trial showed that glucocorticoid corticosteroids stabilize muscle strength and function for up to two years. The most effective prednisolone regime appears to be 0.75 mg/kg/day. Not enough data were available to compare efficacy of prednisone with deflazacort.Adverse effects: Excessive weight gain, behavioural abnormalities, cushingoid appearance and excessive hair growth were all more common with glucocorticoid corticosteroids than placebo. Long-term adverse effects of glucocorticoid therapy could not be evaluated because of the short-term duration of the randomised studies.Non-randomised studies: a number of non-randomised studies with important efficacy and adverse effects data are tabulated and discussed. REVIEWERS' CONCLUSIONS: There is evidence from randomised controlled studies that glucocorticoid corticosteroid therapy in Duchenne muscular dystrophy improves muscle strength and function in the short-term (six months to two years). The most effective prednisolone regime appears to be 0.75 mg/kg/day. In the short term, adverse effects were significantly more common but not clinically severe. Long-term benefits and hazards of glucocorticoid treatment cannot be evaluated from the currently published randomised studies. Non-randomised studies support the conclusions of functional benefits but also indicate clinically significant adverse effects of long-term treatment. These benefits and adverse effects have implications for future research studies and clinical practice.