Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength, predisposing an individual to increased fracture risk. Many factors can lead to the development of osteoporosis. It is usually asymptomatic unless osteoporotic fracture and secondary changes of bone structure occur. Early radiographs show normal findings; however, osteopenic appearance, fracture, cortical bone thinning, and roughening of bone trabeculae can be found according to severity of osteoporosis. These symptoms are most frequently found in the spine and proximal femur. Bone mineral density (BMD) is the standard method used to diagnose osteoporosis, and dual energy X-ray absorptiometry (DXA), one of the measurement tools for BMD, is particularly regarded as the appropriate tool applicable to WHO criteria, which defines osteoporosis as a T-score of less than 2.5 SDs below the mean of young adult women. Peripheral densitometry is less useful in predicting the risk of fractures of the spine and proximal femur, and it is not enough to diagnose and treat osteoporosis. Biochemical bone markers have demonstrated utility in clinical research and trials; however, they cannot replace BMD as a diagnostic tool. WHO recently developed FRAX, a novel method we can use to more conveniently evaluate osteoporotic fracture risk.