Status epilepticus (SE) occurs in children of all ages. Recent epidemiologic investigations of SE show heightened morbidity and mortality in newborns and young infants. However, the existing definition of SE in newborns is not precise and not easily applied in clinical investigations or in clinical practice. To evaluate the underlying conditions, clinical features and treatment of SE in neonates in Japan, a retrospective multi-center study was performed. In the initial investigation, questionnaires were sent to pediatric neurologists in 194 neonatal intensive care units of university hospitals, children's hospitals, and general hospitals throughout in Japan. The questionnaires sought information on the background of each case, types of seizures, etiology of SE, treatments, results and adverse effects of treatment for patients less than 1 week old who had prolonged or frequently repeated seizures lasting more than 15 min and who are refractory to treatment with conventional anticonvulsants, such as diazepam (DZP), phenobarbital (PB) or phenytoin (PHT). As a secondary investigation, 65 cases from nine institutes, which completely fulfilled these criteria and were treated with midazolam (MDL) or lidocaine (Lid) to stop seizures were examined more fully. Subtle seizure and generalized tonic-clonic seizure were the most frequent seizure types. Neonatal SE was most frequently associated with hypoxic-ischemic encephalopathy, followed by intraventricular hemorrhage, central nervous system infections, and cerebral infarction. The final treatment outcome was available for 72.7% and 81.3% of MDL- and Lid-treated patients, respectively. Adverse effects of MDL and Lid were identified in 7.3% and 6.3% of patients, respectively. To reveal electroclinical seizures, clinical seizures without ictal discharge or other non-epileptic movements in neonates was important for appropriate treatment. MDL and Lid were useful drugs for the treatment of neonatal SE.