AIM: To determine the efficacy of the ketogenic diet for children with Lennox-Gastaut syndrome (LGS) at our institution and in the literature. METHOD: The records of children with LGS initiated on the ketogenic diet at our institution from 1994 to 2010 were reviewed. Inclusion criteria included the presence of ≤2.5Hz spike-and-wave complexes on electroencephalogram, multiple seizure types including tonic, atonic, or atypical absence, developmental delay, and age under 1 year. We additionally reviewed the literature for cases of LGS treated with the ketogenic diet and their outcomes. RESULTS: Seventy-one children (41 males, 30 females, median age 3y 6mo, range 18mo-18y), with LGS were initiated on the ketogenic diet. Using an intent-to-treat analysis, after 6 months, 36 (51%) achieved more than 50% seizure reduction, 16 (23%) experienced more than 90% seizure reduction, and 1 (1%) achieved seizure freedom. Results were similar after 12 months. Age, sex, side effects, valproate use, and history of infantile spasms were not predictive of more than 90% seizure reduction. In the literature, 88 of 189 (47%) children with LGS had more than 50% seizure reduction after 3 to 36 months of ketogenic diet treatment. INTERPRETATION: The ketogenic diet is efficacious in the treatment of LGS, with approximately one-half of children responding at 12 months.