Denosumab is a fully human monoclonal antibody that inhibits the formation, function and survival of osteoclasts, preventing the interaction of tumor necrosis factor ligand superfamily member 11 (receptor activator of nuclear factor kappa-B ligand, RANKL) with the tumor necrosis factor receptor superfamily member 11A (osteoclast differentiation factor receptor, ODFR, receptor activator of NF-KB, RANK). This results in a reduction in bone resorption and an increase in bone mineral density. In clinical studies, denosumab has been shown to decrease the risk for vertebral, hip and nonvertebral fractures in women with postmenopausal osteoporosis and the risk for new vertebral fractures in men with nonmetastatic prostate cancer receiving androgen deprivation therapy, with a rate of side effects similar to placebo. A number of clinical trials with denosumab are ongoing to demonstrate its value for other indications and to further characterize its effects on immunomodulation. Denosumab is a new alternative for the prevention and treatment of postmenopausal osteoporosis and a promising agent for the treatment of other bone diseases associated with bone loss.