Hemispheric disconnection has been largely proposed for patients with severe epilepsy associated with a congenital or acquired hemispheric cerebral pathology. The classical procedure of anatomical hemispherectomy was progressively abandoned by neurosurgeons in order to avoid postoperative complications since then hemispherotomy techniques have been developed. Globally, with hemispheric disconnection, the rate of patients becoming seizure-free has been between 50 and 80%. The factors affecting seizure control have not been completely elucidated, but several authors suggested that differences in etiology as well as the hemispheric disconnection technique used may partially explain this variability. The percentage of seizure-free patients is higher with hemispherotomy techniques and in the group of patients with Rasmussen encephalitis, Sturge-Weber syndrome, and vascular insults. Depending on overall long-term progression, there is an improvement compared to preoperative status even if children exhibit heterogenous abilities. The lowest scores are observed for motor skills but communication and socialization are relatively well-preserved and strongly related to the duration of epilepsy: the longer the duration, the lower the scores were. Neuropsychological outcome following hemispheric disconnection makes it possible to study the development of hemispheric specialization during infancy and to provide information on cognitive recovery. Cerebral reorganization has been proved to exist in motor and language recovery. Ipsilateral corticospinal pathways seem to be involved in the movement of hemiplegic limbs. Everyday language can be supported by both hemispheres, but there is an early hemispheric specialization of the left hemisphere according to metaphonologic abilities.