Recognition of the seriousness of the health problems posed by osteoporosis is surprisingly recent, and many general practitioners remain largely unaware of the actual or potential significance of the disorder. Even among specialists there is incomplete consensus on the clinical criteria for screening and on the efficacy of interventions; inevitably, this is reflected in the allocation of health care resources to osteoporosis. WHO has over the last few years supported the development of coordinated knowledge on the etiology, prevalence, and costs to health services of osteoporosis, the evaluation of available techniques for measuring bone mass, mineral density, and turnover, and reviews the various clinical factors that may influence the development of the disorder, including the consideration of risks and benefits as results of intervention. A number of recommendations for future research are advanced. INTERHEALTH programmes offer a framework for the community-based intervention studies, where osteoporosis could be included. There is a need for greater accuracy in assessment of fracture risk, for improved understanding of clinical and other risk factors, and for refinement of prevention strategies and of criteria for selecting individuals for screening, and on the nature and acceptability of interventions. WHO is prepared to participate in this development.