Biomarkers as biochemical substances of collagen metabolism are produced during bone turnover and can be determined as parameters of bone metabolism not only in serum, but also in urine. These growth and decomposition products of the bone are already used to determine bone metabolism in osteoporosis and to prove efficacy of antiresorptive therapy. Metastases of the bone likewise show a higher rate of bone turnover. Nowadays detection of neoplastic bone lesions and progression of their spread are performed with x-rays, radionucleoide bone imaging and magnetic resonance imaging. In the future, biomarkers might improve early detection of bone lesions and follow-up of skeletal metastases. At present, the clinical use is documented insufficiently. In the foreseeable future the determination of the bone turnover markers and additional serum parameters of bone metabolism such as OPG, RANKL might be available for early diagnosis and follow-up in patients with bone metastatic diseases.