RANKL is essential for osteoclast development, activation, and survival. Denosumab is a fully human monoclonal IgG2 antibody that binds RANKL, inhibiting its activity. The aim of this multicenter, randomized, double-blind, placebo-controlled, phase II study was to evaluate the effects of denosumab on structural damage in patients with rheumatoid arthritis (RA) receiving methotrexate treatment.