BACKGROUND: Although the benefits of vision screening seem intuitive, the value of such programmes in junior and senior schools has been questioned. In addition to this there exists a lack of clarity regarding the optimum age, and frequency at which to carry out screening. OBJECTIVES: The objective of this review is to evaluate the effectiveness of vision screening programmes carried out in schools in reducing the prevalence of undetected, correctable visual acuity deficits due to refractive error in school-age children. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) on The Cochrane Library (Issue 3 2004), MEDLINE (1966 to August 2004) and EMBASE (1980 to August 2004). No language or date restrictions were placed on these searches. To date it has not been possible to carry out any manual searches but it is hoped to include these in a future update. SELECTION CRITERIA: We planned to include randomised controlled trials including randomised cluster controlled trials. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed study abstracts identified by the electronic searches. No trials were identified that met the inclusion criteria. MAIN RESULTS: As no trials were identified, no formal analysis was performed. A narrative synthesis of other retrieved studies was undertaken in order to explain current practice. AUTHORS' CONCLUSIONS: At present there are no robust trials available that allow the benefits of school vision screening to be measured. The disadvantage of attending school with a visual acuity deficit also needs to be quantified. The impact of a screening programme will depend on the geographical, and socio-economic setting in which it is conducted. There is therefore clearly a need for well planned randomised controlled trials, in various settings, to be undertaken so that the potential benefits and harms of vision screening can be measured.