Bone metastasis is a frequent complication of cancer disease. The metastatic spread of cancer to bone is common to many different malignancies, particularly breast (ca. 73%), prostate (ca. 68%) and lung (ca. 36%) cancers. Metastases to bone cause increased bone resorption both from direct effects of the tumor itself and thought osteoclastic activation. The diagnosis and follow-up of bone metastatic cancer patients usually relies on skeletal X-ray and bone scintigraphy. However, the development of biochemical markers, used as indicators of bone metabolism, provides data useful in the clinical practice. The most important markers for bone remodeling process, bone formation and resorption, are bone-specific alkaline phosphatase (BAP) and N-telopeptide of type I collagen (NTx), respectively. In this report, we applied two solid-phase immunoassays used for the determination of BAP and NTx in serum of breast cancer (BC) post-menopausal women with bone metastasis and healthy individuals. BAP level in patients was found to be 45.72 +/- 12.92 U/l, while the normal range for healthy individuals was 14.2 - 42.7 U/l. The respective level of serum NTx was 19.20 +/- 8.87 nM bone collagen equivalents (BCE) for patients and 15.9 +/- 3.8 nM BCE for healthy women. Correlation of the obtained data showed elevated levels for both markers indicating high rate of bone degradation in breast metastatic cancer.