BACKGROUND Early predictors of status epilepticus (SE)-associated mortality and morbidity have not been systematically studied in children, considerably impeding the identification of patients at risk. OBJECTIVES To determine reliable early predictors of SE-associated mortality and morbidity and identify the etiology of SE-associated sequelae in Japanese children. METHODS We conducted a prospective multicenter study of clinical findings and initial laboratory data acquired at SE onset, and assessed outcomes at the last follow-up examination. In-hospital death during the acute period and neurological sequelae were classified as poor outcomes. RESULTS Of the 201 children who experienced their first SE episode, 16 exhibited poor outcome that was most commonly associated with acute encephalopathy. Univariate analysis revealed that the following were associated with poor outcomes: young age (⩽24 months); seizure duration >90 min; seizure intractability (failure of the second anticonvulsive drug); biphasic seizures; abnormal blood glucose levels (<61 or >250 mg/dL); serum aspartate aminotransferase (AST) ⩾56 U/L; and C-reactive protein (CRP) levels >2.00 mg/dL. Multivariate analysis revealed that young age, seizure intractability, abnormal blood glucose levels, and elevated AST and CRP levels were statistically significant. CONCLUSIONS Young age and seizure intractability were highly predictive of poor outcomes in pediatric SE. Moreover, abnormal blood glucose levels and elevated AST and CRP levels were predictors that might be closely associated with the etiology, especially acute encephalopathy and severe bacterial infection (sepsis and meningitis) in Japanese children.