Sarcopenia was listed in the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) as M62.84, on October 1, 2016. Sarcopenia is primarily associated with metabolic diseases, such as diabetes, obesity, and cachexia, as well as chronic renal failure, congestive heart failure, and chronic obstructive pulmonary disease. Sarcopenia is also significantly associated with osteoporosis in elderly populations and the combined disease is defined as osteosarcopenia. Several studies have confirmed that sarcopenia and osteoporosis (osteosarcopenia) share common risk factors and biological pathways. Osteosarcopenia is associated with significant physical disability, representing a significant threat to the loss of independence in later life. However, the pathophysiology and diagnosis of osteosarcopenia are not fully defined. Additionally, pharmacologic and hormonal treatments for sarcopenia are undergoing clinical trials. This review summarizes the epidemiology, pathophysiology, diagnosis, and treatment of osteosarcopenia, and includes Korean data.