The primary use of lorazepam, when administered intravenously (IV), has been in the treatment of acute attacks of anxiety and agitation. Recent studies have investigated its efficacy in patients with status epilepticus. The present study compared the efficacy and tolerability of lorazepam and clonazepam in the treatment of status epilepticus. Lorazepam, 4 to 10 mg IV, and/or clonazepam, 1 mg IV, was administered in 61 hospitalized epileptic patients. If needed, the dose of each agent was repeated in 20 minutes. Twenty-two patients were given lorazepam, nine were given clonazepam, and 30 were given both drugs at different times. Improvement in EEG was greater with lorazepam while the clinical symptoms responded more completely to clonazepam. Both drugs were most effective in patients with secondary generalized epilepsy. Drowsiness followed either drug. Psychomotor agitation followed either drug in 12% of patients.