Denosumab (anti-receptor activator of nuclear factorκB ligand [RANKL] antibody) is a novel agent, a fully human monoclonal antibody that inhibits osteoclastic-medicated bone resorption by binding to osteoblast-produced RANKL. By reducing RANKL binding to the osteoclast receptor RANK, bone resorption and turnover decrease. In phase 2 dose-ranging studies, denosumab had a rapid onset and offset effect. Also, in patients who had received 2 years of denosumab and were discontinued for the third year, rechallenge with denosumab during the fourth year demonstrated a return of responsiveness to denosumab that mimicked the initial treatment. Phase 3 pivotal fracture data were recently presented with positive outcome data; denosumab (60 mg subcutaneously every 6 months) significantly reduced vertebral, nonvertebral, and hip fracture risk compared with placebo, and had an excellent safety profile through 3 years of use. Denosumab will offer a novel approach to managing postmenopausal osteoporosis, one that should be associated with a high adherence rate and global fracture risk reduction.