Physicians and other health care providers requesting dual-energy x-ray bone density studies must be able to critically review and interpret such studies. This requires an understanding of the computerized result components of the studies and how such data can be applied in clinical practice. The timing and interpretation of serial bone density studies is governed by the concepts of precision and least significant change. These statistical concepts are well within the purview of the practicing physician. Serial bone density studies cannot be interpreted without prior knowledge of the precision and least significant change of the test.