Twenty five patients in status epilepticus were submitted to treatment by intravenous Valium. Twenty of them were afflicted by chronic cerebral disorders and the others by acute cerebral disorders. The treatment proved to be extremely efficient in the control of the seizures, specially in the cases with chronic lesions. Respiratory depression was observed in only one patient afflicted by acute cerebral lesion. Electroencephalograms obtained during the administration of Valium showed complete extinction of the paroxystic activity, which was replaced, in the normal hemisphere, by well developed beta rythm. In the injured hemisphere the background activity was quite depressed or desorganized and presented little or no beta activity. These findings and those previously reported by others allow the following conclusions: 1) intravenous Valium is presently the drug of choice for the control of any type of status epilepticus; 2) in patients with acute cerebral disorders, the administration of Valium should be made with care, because of its undersirable collateral affects; 3) the electroencephalographic examination during the administration of Valium may be important for the determination of which cerebral hemisphere is injured.