The provocative effects of sleep deprivation (SD) on patients with seizure disorder and on the electroencephalogram (EEG) are well known.The purpose of the study was to test its routine use and usefulness in the pediatric and adolescent age group with, or suspect of having, seizure disorder, especially those presenting with first unprovoked seizure.Between September 2000 and November 2002, among patients referring to the author's clinic and the Pediatric Emergency Department of Nemazi Hospital, Shiraz, 598 children and adolescents were randomly assigned to a 10-minute surface EEG, either routinely, or after a period of partial or total SD. Those who refused or could not tolerate the SD procedure entered the routine group. The EEG's were analyzed for the presence of epileptic abnormality.Of 598 patients, 544( 91%) had clinical seizures; the rest (54, 9%) were seizure suspects or had seizure "mimickers" (syncope, night terrors, pseudo-seizures, etc). Of seizure patients, 210 ( 38.6 % ) suffered from a first unprovoked seizure, and the rest (334, 61.4%) had more than one seizure episode at the time of EEG performance.Abnormal epileptiform EEG's were more frequently seen in the group of seizure patients who were sleep-deprived before performing the EEG, as compared to the routine group. Conversely, more normal EEG's were seen upon routine performance of EEG ( p value <00001, χ 2 = 76.5). Similarly, more abnormal sleep-deprived EEG's were seen in patients with first unprovoked seizure than when EEG was done routinely in this subgroup of patients. Patients with complex partial seizure had significantly more abnormal EEG's when subjected to SD (p<00001).Older patients could tolerate SD better than the younger age group; so more routine EEG's had to be performed in the younger age group.Younger children could only tolerate partial SD. There was no difference in the yield of EEG in patients with absence epilepsy between the two groups. In 5 patients with juvenile myoclonic epilepsy, SD precipitated a generalized tonic-clonic seizure which necessitated acute antiepileptic drug administration to the seizure activity.All patients with non-seizure episodes showed normal EEG's. In conclusion SD can be safely applied in the work-up of selected pediatric patients with seizure disorder, especially in those with their first unprovoked seizure, in whom an abnormal EEG might dictate anti-epileptic drug therapy.Not all children with seizure disorder need to undergo SD for EEG, as it may not Medical