Case-selection strategies have been advocated for identifying patients who would benefit from primary care to prevent osteoporosis. However, the effectiveness of this approach is unclear. To address this question, we performed a randomized control trial to determine whether a case-selection strategy to identify patients with clinical risk factors for osteoporosis, combined with open access to dual X-ray absorptometry (DXA) scans, influences bisphosphonate prescribing in ten GP practices in Avon. Practices were randomized to two groups: the first identified women aged 45–75 years at high risk of osteoporosis and provided open access to DXA scans for 12 months; the second had no case-finding strategy and no DXA scan access. Bisphosphonate prescribing was ascertained by searching computerized patient records every 3 months during the intervention and a subsequent 6-month follow-up period. Overall, the number of subjects in each practice who were prescribed bisphosphonates increased by 50% (p<0.001), and the proportion of bisphosphonates prescribed as aminobisphosphonates increased 3-fold (p<0.001). The magnitude of these changes was similar in both groups. However, of the patients prescribed bisphosphonates, approximately twice as many in group 1, as compared with group 2, had a previously documented low-trauma fracture, as assessed at the end of the 12-month intervention period (p=0.01). Furthermore, at study’s end, of the 30 patients in group 1 receiving bisphosphonates who had received DXA scans, 80% had osteoporosis as defined by t-score<-2.5. We conclude that use of a case-selection strategy for osteoporosis in primary care, combined with open access to DXA scans, appears to target bisphosphonate therapy to those at high risk of osteoporotic fractures. In contrast, the overall rate of bisphosphonate prescribing is unaffected by this intervention.