Abstract: The bone turnover markers were composed from the metabolic products of bone matrix and bone cells. The changes of these markers levels in serum and/or urine represents the status of bone metabolism. To measure the levels of these markers will be given important information for evaluating the diagnosis and the responses of therapALPy in metabolic bone diseases, and for predicating the risks of bone fracture. The biochemistry, measurement and clinical apALPplication will be introduced briefly in this papALPer.