This paper presents a summary of the evidence review group (ERG) report into denosumab for the prevention of osteoporotic fractures in postmenopausal women. Denosumab has been shown in a large randomised trial to reduce the frequency of osteoporotic fractures when given subcutaneously at 6-monthly intervals. Compared with placebo, the relative risks of clinical vertebral and hip fractures were 0.32 and 0.60, respectively. Clinical vertebral fractures occurred in 0.8% of women taking denosumab and 2.6% of control subjects. Hip fractures occurred in 1.2% of women on placebo and 0.7% on denosumab. The expected use is in women who cannot tolerate oral bisphosphonates. Other options in that situation include strontium ranelate and zoledronate, which, compared with placebo, also reduced the risk of clinical vertebral fractures [relative risk (RR) 0.65 and 0.23, respectively]. Zoledronate also significantly reduced the risk of hip fractures (RR 0.59). The ERG concluded that zoledronate was the main comparator. The relative cost-effectiveness of denosumab and zoledronate depends mainly on assumptions about costs of administration.