Encephalopathy with electrical status epilepticus in sleep (ESES) syndrome is a rare form of epilepsy in childhood. Results of treatment with antiepileptic medications or immunotherapy are variable. Epilepsy surgery should be considered in patients with a symptomatic cause. Cognitive outcome is more favorable in patients with an idiopathic form. Any newly observed seizure type or behavioral or developmental/cognitive symptom in children aged younger than 10 years with focal epilepsy should alert the clinician to the possibility of ESES syndrome. The exact pathophysiological mechanisms of ESES and associated functional impairments are still unresolved.