Hemimegalencephaly is a rare and often severe congenital malformation of the brain that gives rise to epilepsy. It occurs when the nervous system develops abnormally, leading to an irregular cerebral cortex formation. The cause of this condition is unknown and it is usually diagnosed at birth. Similar to other forms of pediatric epilepsy, hemimegalencephaly may be treated by both medical and surgical means depending on the severity of the condition and how the patient is responding to other forms of treatment. Hemimegalencephaly is very hard to treat with medication, and surgery is often the best course of action. A hemispherectomy is a surgical procedure that can offer predictable results and improve the outcome for patients who are appropriate candidates.