We assessed the clinical usefulness of quantitative ultrasound (QUS) in defining the prevalence rates of osteoporosis and osteopenia and their association with fractures of the forearm, vertebrae, and hip. The ESOPO study was conducted in 2001 and assessed a random sample of 11,011 women and 4,981 men, in 83 centers spread all over Italy. A large array of risk factors was investigated, and self-reported history of fractures was collected in a questionnaire. After the patient had undergone interview and a brief physical examination, QUS of the heel was performed, using the Achilles apparatus (GE-Lunar, Madison, USA). The prevalence rate of osteoporosis in women 40-79 years old was approximately 18.5%, while the rate of osteopenia was about 44.7%; in men 60-79 years of age the rates were 10% and 36%, respectively. A strong association with fractures was found for osteoporosis and osteopenia in both men and women, independently of all traditional risk factors, including age. These results confirm the suitability of US measurements as a tool for detecting individuals at risk of fractures.