OBJECTIVES To determine the budget impact of incorporating zoledronic acid to treat post-menopausal osteoporosis in Brazilian public reimbursement system. METHODS This study considered only postmenopausal women with osteoporotic hip fracture above the age of 65. According to DATASUS (public healthcare system's database), in 2007 there were 11,666 women with these characteristics. The mortality rate considered for this population was higher than for those of general population. It was applied a relative risk found on literature review for post-fracture years on IBGE's (Brazilian Institute of Geography and Statistic) mortality rate by other causes. Only direct medical costs were considered. Based on DATASUS, the follow-up exams costs were equivalent to US$37.37 (conversion rate in March 16th = R$2.27/USD 1.00) per year per patient. The average cost of procedure to treat the fracture was extracted from Tabwin (public health care system's database). The annual costs with zoledronic acid and sodium alendronate were US$341.99 and US$12.68, respectively. It was presumed 5% per year as zoledronic acid market share in this population and the remaining patients of each year would continue the treatment with alendronate. RESULTS The annual impact estimated for 3 consecutive years is US$1.6 million for National public health care system. CONCLUSIONS If only post-menopausal women over 65 years old with osteoporotic hip fracture were eligible to zoledronic acid treatment, and presuming that only 5% of this patients per year would take this medication, an incremental expense of approximately US$1.6 million per year was estimated in this analysis. It is expected that this annual increase does not continue for many years, once the population eligible to treatment is elderly.