BACKGROUND AND OBJECTIVES: In patients without a prevalent fracture, guidelines recommend initiating therapy based on a calculation of absolute fracture risk. Two common calculators are used in Australia - FRAX (Australia) and Garvan Fracture Risk Calculator (Garvan). The aim of this article is to examine whether the decision to treat with bone-preserving medication would be different depending on which calculator was used. METHOD: Data were entered into each calculator for hypothetical male and female patients, aged 50-85 years, with femoral neck t-scores from +3.0 to -3.0. RESULTS: Garvan consistently predicted a higher absolute fracture risk than FRAX (Australia). The discrepancy increased with increasing age and decreasing bone mineral density, and was most pronounced in the prediction of any fracture, but less so for hip fracture. DISCUSSION: The decision to prescribe osteoporosis medications for a patient on the basis of fracture risk may depend on which risk calculator is used. Differences in the calculator methods contribute to the discrepancy between them.