We evaluated the efficacy and safety of lorazepam (LZP) 4 mg for adults (age, 16 years old or older) or 0.05mg/kg for children (age, 3 months to less than 16 years) as a slow intravenous injection in 26 Japanese patients with status epilepticus or repetitive seizures. The proportion of patients whose initial seizure stopped within 10 minutes and who continued seizure-free for at least 30 minutes after the completion of initial dose as the primary endpoint was 48.0% (12/25, 95%CI: 27.8%-68.7%). However, the proportion of patients whose seizures stopped within 10 minutes and who continued seizure-free for at least 30 minutes after the completion of either initial or second dose (in 10 to 30 minutes from the initial dose) was 64.0% (16/25, 95%CI: 42.5%-82.0%) in total, and 77.8% and 56.3% in adults and children, respectively. The most common adverse events (AEs) were somnolence (7.7%) and insomnia (7.7%), and almost all AEs were mild or moderate in severity. No patient experienced serious or severe LZP-related AEs. No one discontinued the study due to AEs.