The invasive Red Imported Fire Ant (Solenopsis invicta Buren) is well established at two locations in the Brisbane area, and we report a patient with anaphylaxis after a sting. The potential for anaphylactic events in Australia due to S. invicta will be greater than for native ants because of its unusual venom, its habit of forming supercolonies in grassy areas, and its aggressive group territorial defence, which can result in multiple stings.