Denosumab (Prolia®) is a human recombinant monoclonal antibody that is approved for the treatment of postmenopausal osteoporosis in women at high or increased risk of fracture in the US, the EU and several other countries. Denosumab has a novel mechanism of action; it binds to receptor activator of nuclear factor κB ligand and inhibits bone resorption by inhibiting osteoclast formation, function and survival. In postmenopausal women with osteoporosis, denosumab reduced the risk of vertebral, nonvertebral and hip fractures compared with placebo over 3 years in the large, phase III FREEDOM study. In postmenopausal women with low bone mineral density (BMD) or osteoporosis, treatment with denosumab increased BMD and decreased markers of bone turnover more than alendronate in those who were essentially treatment-naive in the 1-year DECIDE study and also in the 1-year STAND study, in which women were switched from alendronate to denosumab or continued alendronate treatment. Denosumab was generally well tolerated in clinical trials, although long-term effects of very low bone turnover remain to be established. Denosumab is administered once every 6 months via subcutaneous injection, which may be a preferred method of administration and may improve adherence to treatment compared with other osteoporosis treatments. Denosumab is a valuable new option for the treatment of postmenopausal osteoporosis in women at increased or high risk of fractures, and may be useful as a first-line treatment in women at increased risk of fractures who are unable to take other osteoporosis treatments.