Resective surgery is an accepted treatment modality for medically intractable focal epilepsy in children as well as in adult. During the presurgical evaluation processes, intracranial neurophysiologic recording of epileptiform abnormalities have been used much more commonly in adults and older adolescents than in infants and children. However, as infants and children are increasingly referred for early surgery in many centres, it may be necessary to study complex cases in some children with invasive electrodes in order to plan a safe and effective resection. This article gives first an overview of the rationale and indications, with case illustrations, for using these techniques. This is followed by general discussions on individual electrodes and their use in infants and children.