Objective: A systematic review of the available literature on the effectiveness of knee-ankle-foot orthoses in the treatment of Duchenne muscular dystrophy. Design: A computer search was carried out (MEDLINE 1966-97, CINAHL 1982-97) using the key words muscular dystrophy, rehabilitation, locomotion, braces or orthotic devices. References in relevant publications and nonindexed journals were also examined. Criteria to include and exclude articles were formulated. We used a systematic review procedure to evaluate the literature. Seven methodological criteria were formulated. Results: Thirty articles describing 35 studies met the inclusion criteria for our review, nine studies were selected based on completeness of information on study population, treatment and quantitative presentation of the effect outcome. Operations on the lower limbs were performed on most patients. A concomitant programme of rehabilitation was not described thoroughly. A percentage success of treatment was calculated for eight studies. Median percentage after one year was 75.1, after two years 47.9 and after three years 24.3. The median for the means of independent walking was 24 months, the median for the means of assisted walking was 36.2 months and the median for the means of standing ability was 50.5 months duration. Conclusion: The scientific strength of the studies reviewed is poor. It seems that the use of knee-ankle foot orthoses can prolong assisted walking and standing, but it is uncertain whether it can prolong functional walking. The boys that benefit most have a relatively low rate of deterioration, are capable of enduring an operation and are well motivated.