The most useful methods for estimating fracture risk are bone mineral density (BMD) testing by dual-energy x-ray absorptiometry and consideration of clinical risk factors (CRFs) for fracture. The combination of BMD and CRFs predicts fractures better than BMD or CRFs alone. FRAX is a computer-based fracture risk algorithm developed by the World Health Organization to estimate fracture probability using validated CRFs and femoral neck BMD, when available. BMD and FRAX are included in clinical practice guidelines to identify patients at high fracture risk who are most likely to benefit from pharmacologic therapy to reduce fracture risk.