Recent evidence suggests that vitamin D and calcium can reduce the incidence of hip fracture amongst elderly women. We estimated the costs of using either parenteral vitamin D alone, or oral vitamin D plus calcium, in a number of treatment strategies. These were: all women in a community setting; women with low body mass index (BMI) in the community; women in nursing homes; women with low BMI in nursing homes. The cost per averted fracture amongst women living in the community through the use of parenteral vitamin D alone was 946 pounds, and the cost per averted hip fracture was 2317 pounds. Inclusion of calcium significantly increased the cost to 14, 240 pounds for any fracture and 22, 379 pounds for hip fractures. However, targeting either treatment on women with the lowest BMI reduced the cost of averting a hip fracture, as did targeting women living in nursing homes. After removing cost savings from treatment costs, savings to the NHS occurred for all parenteral vitamin D strategies but only one of the oral vitamin D and calcium strategies. Preventing fractures with injectable vitamin D is likely to produce savings for the NHS. The addition of calcium will increase costs significantly unless the intervention is targeted on those at high risk.