Thromboprophylactic medicine is provided routinely to patients who present to emergency departments (EDs) with lower leg fractures as a preventive measure against forming blood clots in an immobilised limb. A large amount of medicine is provided to these patients at discharge, but once they have recovered their mobility the remaining medicine is unusable and must be destroyed. There is a lack of data to quantify this waste. This article reports a service evaluation that was conducted in an ED to investigate the wastage and the cost implications of this treatment protocol. It shows that over half the medicine dispensed is subsequently wasted and makes recommendations for changing dispensing practice.