The burden of osteoporosis in developing countries is increasing dramatically with the aging of the population and demographic trends; however, there is a lack of direct epidemiologic data. There are clear differences at present between and within populations that limits the validity of many estimates and more data is needed. Existing data and estimates are considered in terms of bone mass, bone structure, 10-year and lifetime probability of fracture, numbers sustaining fractures, the outcome of fracture, importance of differences in fracture management, and risk factors for their occurrence and outcome. Future trends are also considered.