A method of treating and/or preventing symptoms of Lennox-Gastaut Syndrome (LGS) also known as Lennox Syndrome in a patient such as a patient previously diagnosed with Lennox Syndrome, by administering an effective dose of fenfluramine or its pharmaceutically acceptable salt to that patient. Lennox Syndrome patients are treated at a preferred dose of less than about 2.0 to about 0.01 mg/kg/day.
