Osteoporosis and sarcopenia lead to increased mortality, but their early diagnosis allows preventive measures and treatment to be implemented. The dual-energy X-ray absorptiometry (DXA) method enables the assessment of both bone mineral density (BMD) and bone quality based on the trabecular bone score (TBS), the Bone Strain Index (BSI), hip structure analysis (HSA), and comprehensive hip axis length (HAL). The main complications of osteoporosis are fractures, and a BMD value or T-score together with TBS can be also applied in fracture risk calculation using the Fracture Risk Assessment Tool (FRAX). In recent years, the interest in sarcopenia has increased. There are many methods for assessing the quality, quantity and function of muscles. Total body DXA provides information not only about the BMD of the whole skeleton or the amount of lean tissue (identified as fat-free mass), but also about the amount and distribution of adipose tissue. Some parameters obtained from DXA measurements related to muscle and/or fat mass are used in the assessment of osteosarcopenia. The following article presents a wide range of possibilities for the use of the DXA method in the diagnosis of osteosarcopenia because DXA is a useful technique for the diagnosis of bone density and body composition together.