&NA;Intraoperative brain mapping techniques were used to localize language cortex, sensorimotor pathways, and seizure foci in children with supratentorial brain tumors. The methods of direct cortical and subcortical stimulation, in addition to electrocorticography, enabled us to maximize tumor resection, minimize morbidity, and eradicate epileptogenic zones which were always adjacent to, but not involving, the tumor nidus. Language localization was found to be quite variable in the children tested and anatomically unpredictable based on the preoperative neurological or radiological examination. Physiological mapping techniques, therefore, appear to be safe, reliable, and very useful for operations on tumors located within or adjacent to eloquent brain regions in the pediatric population. (Neurosurgery25:786‐792, 1989)