More than half of all women and about one third of men will experience osteoporotic fractures during their lives. Although no symptoms occur prior to fracture, bone mineral density and other risk factors can be used to identify high-risk patients, and because effective interventions exist, many of these fractures are now preventable. The proportion of people who are affected, the mortality and morbidity resulting from osteoporotic fractures, and the major known risk factors are discussed. Greater attention should be given to measuring bone mineral density and identifying other risk factors to quantitate the degree of fracture risk among patients (with or without a history of previous fractures), because the consequences of fractures often are severe, and no symptoms other than fractures are associated with disease progression.