OBJECTIVE: The pathogenesis of electrical status epilepticus during sleep (ESES) in children remains unknown. We undertook a retrospective study of epileptic children who presented with ESES to investigate the correlation factors of ESES. METHODS: Thirty epileptic children with ESES (ESES group) and 30 age-and sex-matched epileptic children without ESES (control group) admitted to Maternal and Child Health Care Hospital of Tangshan between January 2000 and July 2006 were enrolled. The results of questionnaire and laboratory examinations were compared between the two groups. RESULTS: Nine patients had a family history of epilepsy in the ESES group, but only 2 patients in the control group (P<0.05). Language disorder was found in 11 patients in the ESES group, but only 2 patients in the control group (P<0.05). Thirteen patients were confirmed with epileptic syndrome in the ESES group, but only 5 patients in the control group (P<0.05). Twentyfive patients in the ESES group showed mental retardation, but only 5 patients from the control group (P<0.01). CONCLUSIONS: ESES may be correlated with family history of epilepsy, epileptic syndrome, mental retardation and language disorder.［Chin J Contemp Pediatr, 2009, 11 (2):110-112］