PURPOSE: Surgical approach with medically intractable epilepsy has increased with recent advances in neurodiagnostic modalities. This study was designed to review the clinical manifestations and surgical outcome of patients who received hemipherotomy. METHODS: We performed a retrospective study of 19 patients under 15 years old who had medically intractable epilepsy and underwent hemipherotomy at Severance Children's Hospital between 2003 and 2008. RESULTS: Eleven patients(57.9%) showed Engel Class I outcome, 6 patients(31.6%) showed Engel Class II and 1 patient(5.3%) showed Engel Class III outcomes. Preoperative evaluation revealed concordance in all 19 patients(100%) on MRI, 17 patients(89.5%) on long-term EEG monitoring, 17 patients(89.5%) on PET and 13 patients(68.4%) on interictal SPECT. Malformation of cortical development was the most common etiology(4 patients, 21.5%). Other etiologies included hemimegalencephaly, Sturge-Weber syndrome, hemorrhage, infarction and schizencephaly(2 patients each, 10.5%). The most common pathologic finding was cortical dysplasia(9 patients, 49.4%). Other pathological findings included microdysgenesis(2 patients, 10.5%), gliosis(4 patients, 21.1%), leukomalacia, Lafora body and calcification in cortex(1 patient each, 5.3%). CONCLUSION: Surgical outcome of hemipherotomy in infant and children were favorable. Better evaluation through utilization of advanced neurodiagnostic modalities including EEG monitoring and neuroradiologic studies will greatly improve postsurgical outcome of hemipherotomy.