There is scanty data regarding the efficacy and tolerability of the modified Atkins diet in children with Lennox-Gastaut syndrome. This study was a retrospective review of children with Lennox-Gastaut syndrome treated with the modified Atkins diet from May 2009 and March 2011. The diet was initiated in those children who persisted to have daily seizures despite the use of at least 3 appropriate antiepileptic drugs. Twenty-five children were started on a modified Atkins diet, restricting carbohydrate intake to 10 g/d. After 3 months, 2 patients were seizure-free, and 10/25 children had >50% reduction in seizure frequency. At 6 months, of 11 patients on the diet, 3 were seizure free and 8 had >50% reduction in seizure frequency. At 1 year, all 9 children on diet had >50% reduction in seizure frequency. The side effects of the diet were mild. The modified Atkins diet was found to be effective and well tolerated in children with Lennox-Gastaut syndrome.