Twelve patients suffering from intractable epilepsy and presenting with radiological evidence of diffuse hemispheric involvement of a dysplastic process, were treated by disconnective hemispherectomy, either functional hemispherectomy or peri-insular hemispherotomy. The median age at surgery was 4.5 years old and the interval between seizure onset and surgery, 3 years. All patients underwent a presurgical evaluation that led to the suggestion of disconnective hemispherectomy. Over 70% of patients have remained in Engel's seizure outcome class I since surgery and another 18% have had a satisfactory seizure outcome. There was one unexplained death and one case of early hydrocephalus. Hemispherectomy offers the possibility to improve seizure control in the majority of patients undergoing surgery for extensive dysplastic pathology of the hemisphere. Disconnective techniques reduce the rate of complications in this specific pathology