Assessment of BMD has become the essential part of evaluation of patients at risk of osteoporosis. It is likely that different BMD technologies will coexist in clinical practice in the future depending on varying clinical needs. DXA is currently the leading bone density technique because it has the capacity to measure axial and appendicular sites, superior monitoring capabilities, and more sophisticated reference databases and quality control procedures. More rapid and portable peripheral devices, such as peripheral DXA, peripheral instantaneous x-ray imager, and QUS, will likely be used for screening. This large variety of available bone densitometry techniques will provide a wide selection for clinicians to choose from. It may also add confusion, however, about which devices should be used and how to interpret data from different techniques. It is critical for clinicians to have a basic understanding of the technology being used, and the clinical advantages and disadvantages of each instrument, to choose properly which test to perform and interpret the obtained results. When combined with other major risks for fracture, such as age and prior fragility fractures, knowledge of the BMD is an invaluable tool in the assessment of patients with known or suspected osteoporosis.