In the last decade biochemical markers of bone turnover have gained a wide-scale clinical utility in the assessment of hip fracture risk in elderly patients and monitoring the efficacy of anti-resorbtive drugs, SERMs and HRT treatment. The identification of some bone specific molecules (osteocalcin) and collagen I degradation products (C- and N-telopeptides) and their application in addition to routine anorganic compounds (Ca, P) and alkaline phosphatase activity measurements led to the possibility of exact quantification of bone turnover. There is an increasing evidence that the osteoclast-regulator proteins: osteoprotegerin (OPG) and RANKL play a key role in bone metabolic homeostasis and could be used to assess the regulatory balance of bone remodelling in completion of the circulating biomarkers mentioned above. At present, there are well-established riskscreening/ monitoring criteria for osteoporosis, but new scientific data could bring substantial improvement of previously obtained results.