BACKGROUND: Hip fracture in the elderly is usually the result of a simple fall. Hip protectors have been advocated as a means to reduce the risk of sustaining a fracture in a fall on the hip. OBJECTIVES: To determine if external hip protectors reduce the incidence of hip fractures in elderly persons following a fall. SEARCH STRATEGY: The Cochrane Musculoskeletal Injuries Group trials register, MEDLINE, and reference lists of relevant articles were searched, and identified trialists contacted. Date of the most recent search: July 2000. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing the use of hip protectors with a control group. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality, using a ten item scale, and extracted data. Additional information was sought from all trialists. Wherever appropriate and possible, the data are presented graphically. MAIN RESULTS: Six randomised trials involving 1752 participants were included within the review. All studies involved elderly people in nursing homes or residential care, three within the Scandinavian countries, one in Japan, one in the United Kingdom and one in Australia. The two largest studies involving 1409 participants randomised by nursing home or nursing home ward rather than by the individual (cluster randomisation). One study of 141 individuals was primarily a compliance study. Summation of results from the other five studies gave an occurrence of hip fractures of 16/660 (2.4%) for those allocated to wear hip protectors, against 63/951 (6.6%) to those not allocated to wear protectors. However due to the large number of participants allocated by cluster randomisation it was not possible to demonstrate conclusively that this difference between groups was statistically significant. Only one of the 16 hip fractures that occurred in the individuals allocated to wear hip protectors occurred whilst the protector was worn. No significant adverse effects of the hip protectors were reported but compliance, particularly in the long term, was poor. REVIEWER'S CONCLUSIONS: Hip protectors appear to reduce the risk of hip fracture within a selected population at high risk of sustaining a hip fracture. However, this conclusion is based on five trials of low to moderate quality. As two used cluster randomisation, pooling of data was limited. The generalisation of the results is unknown beyond high-risk populations. Results from eleven ongoing trials may clarify this situation. Acceptability by users of the protectors remains a problem, due to discomfort and practicality.