Epilepsy is the most common serious neurological condition in the world, with an estimated prevalence of 1% of the population. The highest incidence occurs in childhood and in the elderly, with lower levels in early adulthood. Traditional epilepsy management includes pharmacological treatment, epilepsy surgery, and vagal nerve stimulation. Despite these therapies, 25% of children continue to have uncontrolled seizures. The ketogenic diet (KD), which has been in use since 1921, is a treatment option for many of these children. A meta-analysis of 19 studies with a combined sample of 1084 pediatric patients was completed in 1998 by Blue Cross Blue Shield. Estimates of the overall efficacy of the KD in controlling seizures were reported as follows: 16% became seizure free, 32% had a >90% reduction in seizures, and 56% had a >50% reduction. The KD is high in fat, moderate in protein, and low in carbohydrates. This combination of energy results in a sustained ketosis that somehow serves to abate seizures through an unknown mechanism. Strict adherence to the diet is required for it to be effective. Newer, more liberal versions of the KDs have been recently introduced and are being studied in children and adults. Administration of all of these metabolically adjusted diets must be medically managed as there can be adverse effects. The focus of this review is on the pediatric application of the KD.