Hemispherectomy is the most dramatic type of brain resection performed for epilepsy. Introduced by McKenzie in 1938,(1) it is indicated for intractable seizures that predominantly first occur in infancy and early childhood, arise diffusely from one hemisphere, and are associated with unihemispheric insults. These include hemimegalencephaly, other multilobar cortical dysplasias, perinatal strokes, Sturge-Weber syndrome, and Rasmussen encephalitis. Improvements in surgical techniques and patient selection criteria have resulted in lower complication rates, including lower mortality. Because hemispherectomy is often performed in children who already have moderate to severe hemiplegia, the added motor deficits from the surgery are generally low. Furthermore, given the plasticity in the developing brain, surgery when done early may allow reorganization and preservation of both motor and cognitive function.