Fundamental cytokine regulating remodelation of the skeleton is receptor activator of nuclear factor kappa B ligand (RANKL). RANKL is counter regulated by soluble receptor osteoprotegerin (OPG). While RANKL activates osteoclastic bone resorption, the OPG stimulates bone formation. RANKL/OPG system (TRANCE axis) is activated in favour of RANKL in estrogen deficiency, inflammation, bone malignancies and during the treatment with glucocorticoids. TRANCE axis is functional also in other tissues including vessel wall, where dysbalance with superiority of RANKL leads to atherogenesis. Molecules blocking RANKL (specific antibodies and OPG) are potential drugs for treatment of osteoporosis, atherosclerosis, inflammation diseases, myeloma or osteolytic bone metastases. This review is focused on pathogenetic role of TRANCE axis in the development of osteoporosis and atherosclerosis and on its use in diagnosis and treatment of both degenerative diseases.