The etiological and precipitating factors, clinical features and outcomes of 48 patients over the age of 17 years with generalized major motor status epilepticus were studied. Eleven patients were regarded to have idiopathic epilepsy and the other thirty-seven had symptomatic epilepsy due to intracranial infection, cerebrovascular diseases, cerebral tumors, cerebral trauma, metabolic disorders, unknown and others. Most frequent causes were intracranial infection including nonspecific inflammatory granuloma, cerebral cysticercosis, viral encephalitis and sequela of previous meningitis. The major single precipitating factor of the status was abrupt discontinuation of antiepileptic drugs and this accounted for 57% of the status in 30 patients with previous seizures. Other factors were upper respiratory infection, alcohol intake and physical exhaustion. In 18 patients without history of previous seizure, only six had obvious precipitating factors. Among 48 patients, sixteen patients showed primary generalized tonic-clonic status and the remaineder had generalized tonic-clonic status with focal onset. Twenty-five patients (78%) in the latter group had apparent causes and brain C.T. scans revealed structural lesions in 68% of 28 patients in the latter group. Therefore it is suggested that patients showing the status with focal onset must be screened with laboratory studies as fully as possible, including brain C.T. In 41 patients who had no apparent ifectious process, the episodes of status were accompanied by hyperthermia (69%) and transient leukocytosis (65%). In 16 of them, cerebrospinal fluid was examined and a status-induced cererbrospinal fluid pleocytosis was observed in 3 patients. Forty-two patients in this series recoverd without neurological sequelas from the status and three had some sequelae at the time of discharge, including disturbances of recent memory, calculation, judgement and emotion. Three patients (6%) who died from the status were having idiopathic epilepsy, viral encephalitis or subarachnoid hemorrhage, respectively.