OBJECTIVES Persistence with osteoporosis medications is a significant clinical issue, with many patients discontinuing therapy after just one year. The purpose of this study was to estimate the lifetime clinical and economic impact of poor persistence among patients with osteoporosis in Brazil. METHODS We used modeling techniques and data from secondary sources to quantify the impact on risks, costs, and consequences of hip fracture resulting from poor persistence with osteoporosis medications. All patients entering the model were assumed to be 65-year-old postmenopausal women, recently diagnosed with osteoporosis, and newly initiated on bisphosphonate therapy. The model calculates the risk of hip fracture as well as fracture-attributable life-years lost and health care costs (acute and follow-up). To estimate the impact of poor treatment persistence on these measures, we contrasted model results for a scenario assuming perfect compliance with therapy over each patient's remaining years of life to another assuming all patients would discontinue therapy after one year. Analyses were performed for all patients and for a subgroup with more severe disease (t-score RESULTS We estimate that Brazilian patients who discontinue osteoporosis therapy after one year would experience 27.0 additional fractures per 100 patients, lose an average of nearly one year of life (0.968 fracture-attributable life years), and incur an average of R$3611 in additional costs of fracture-related care compared with perfectly compliant patients. Corresponding numbers for the subgroup of patients with severe osteoporosis are 35.5 additional fractures (per 100), 1.31 fracture-attributable life-years lost, and R$5,603 in fracture-related health care costs. CONCLUSIONS The lifetime clinical and economic consequences of poor persistence among osteoporosis patients in Brazil may be considerable. Programs to improve persistence with osteoporosis medications have the potential to benefit patients and payers alike.