Complex partial status epilepticus (CPSE) is often under-diagnosed, especially in children. The aim of this study was to clarify the characteristics and pathophysiology of CPSE in children with epilepsy.We retrospectively reviewed the medical records and EEGs of 17 children with epilepsy who were diagnosed as having CPSE by ictal or postictal EEGs to investigate clinical and EEG features.The ages at diagnosis of CPSE ranged from 3 months to 17 years. At the time of diagnosis of CPSE, 13 patients had symptomatic localization-related epilepsy, two had epilepsy with continuous spike-waves during slow wave sleep, and each patient had cryptogenic localization-related epilepsy and idiopathic localization-related epilepsy. Only subtle symptoms including autonomic ones associated with disturbance of consciousness were the main clinical features in 12 of 44 CPSE episodes. Another 22 episodes showed minor focal motor elements, and the other 10 had major convulsive phase during or immediately before CPSE. Ictal EEGs of CPSE were divided into three types according to the degree of high-voltage slow waves (HVS) and spike components. Ictal EEGs could show spike-dominant or spike and HVS mixed patterns even if patients showed only subtle symptoms. The epileptogenic areas estimated by the ictal or postictal EEGs showed variability with only two cases of temporal origin.The close observation of clinical symptoms such as various subtle symptoms and/or mild convulsive elements and ictal EEGs are absolutely needed for the diagnosis of CPSE in children.