[en] Denosumab has recently been shown to be safe and to significantly reduce the risk of vertebral, hip and non-vertebral fractures in the "Fracture REduction Evaluation of Denosumab in Osteoporosis every 6Months" (FREEDOM) Trial. Besides the clinical profile of a new drug, it becomes increasingly important to assess whether the drug represents good value for money. This study aims to examine the potential cost-effectiveness of denosumab in the treatment of postmenopausal osteoporotic women. An updated version of a validated Markov microsimulation model was used to estimate the cost (euro2009) per quality-adjusted life-year (QALY) gained of a 3-year denosumab treatment compared with no treatment. The model was populated with cost and epidemiological data for Belgium from a health-care perspective and the base-case population was defined from the FREEDOM Trial. The effect of denosumab after treatment cessation was conservatively assumed to decline linearly over 1year. Uncertainty was investigated using one-way and probabilistic sensitivity analyses. In particular, additional analyses were performed in populations (over 60years) where osteoporosis medications are currently reimbursed in many European countries, i.e. with bone mineral density (BMD) T-score</=-2.5 or prevalent vertebral fracture. In the base-case analysis, the cost per QALY gained of denosumab compared with no treatment was estimated at euro28,441. This value decreased to euro15,532 and to euro11,603 for women with a BMD T-score of -2.5 or prevalent vertebral fracture, respectively. Additional analyses showed that the cost-effectiveness of denosumab fall below commonly accepted threshold of euro30,000per QALY gained for women with a BMD T-score </=-2.5 or prevalent vertebral fracture, over the entire age range examined (60-80years). The results were robust under a wide range of plausible assumptions. In conclusion, this study suggests, on the basis of currently available data, that denosumab is cost-effective compared with no treatment for postmenopausal Belgian women with low bone mass and who are similar to patients included in the FREEDOM Trial. In addition, denosumab was found to be cost-effective in population currently reimbursed in Europe with T-score</=-2.5 or prevalent vertebral fracture, aged 60years and above. Additional data are needed on the relative cost-effectiveness compared with other anti-osteoporotic agents and on the long-term safety of denosumab.