Over the past decade, bone density scanning has come to be seen as an essential part of the evaluation of patients at risk of osteoporosis. Although dual x-ray absorptiometry (DXA) is the technique most associated with the recent growth in bone densitometry, several innovative devices for performing measurements at sites in the peripheral skeleton are also available. This article examines the question of whether there is any one method or measurement site that performs better than all the others at identifying patients at risk of fracture. Given that it is essential to make greater use of the small, low-cost peripheral devices if the many millions of women most at risk are to be identified and treated, what approaches to the interpretation of bone density scans can be adopted to ensure the greatest degree of consistency among different methods? Finally, does it matter if the imperfect correlation among different types of measurement results in different patients being selected for treatment on the basis of different techniques?