Rationale, aims and objectives: There is considerable uncertainty around the cost-effectiveness of interventions for preventing secondary falls in older people presenting to emergency departments (ED). The objective was to complete an economic evaluation of a brief educational ED intervention aimed at preventing falls in older people post discharge. Methods: A net cost analysis was completed from the health system perspective, using data from a controlled clinical trial, where an education intervention was compared to standard care. Patients aged 65 and older presenting to the ED with any diagnosis were enrolled. The costs, using Australian dollars (A$) at 2015 values, included resources required for the intervention and any health care cost incurred in the 6-month follow-up period (time horizon). Cost data were sourced through institutional billing records and liaison with the patient and their general practitioner. Mean costs and differences were analysed through nonparametric bootstrapping. Results: The total costs in the control group (n = 201) were A$1 576 496 compared to A$1 292 130 in the intervention group (n = 211). The mean net cost per patient was A$7749 and A$6187 (P = 0.68) respectively resulting in a mean difference of A$1580 per patient in the intervention group (95% CI: A$−2806 to A$6150). Patients who presented to the ED with a fall diagnosis were reviewed through subgroup analysis. Total costs for patients who presented with a fall in the control group (n = 69) were A$708 995 compared to A$512 874 in the intervention group (n = 97). The mean net cost per patient was A$10 326 and A$5343 respectively (P = 0.33) with an overall saving of A$4624 per patient in the intervention group (95% CI: A$−2868 to A$15 426). Conclusions: A brief intervention had no net cost benefit across the whole study population, but is more cost effective in older people presenting to the ED with a fall.