Diazepam is administered to children in status epilepticus by paramedics in many Emergency Medical Services systems throughout the United States despite the lack of clear evidence that this therapy is safe and effective when employed in the prehospital environment. We reviewed the clinical course of 45 episodes of generalized convulsive status epilepticus (SE) in 38 children to determine the effect of prehospital diazepam therapy (given rectally or intravenously) on the clinical course of SE and subsequent patient management. Nineteen SE episodes were treated with prehospital diazepam therapy--9 episodes with rectal diazepam (mean dose: 0.6 mg/kg) and 10 episodes with intravenous diazepam (mean dose: 0.2 mg/kg). Prehospital diazepam therapy was associated with SE of shorter duration (32 min vs 60 min; P = .007) and a reduced likelihood of recurrent seizures in the emergency department (58% vs 85%; P = .045). There were no significant differences between rectal and intravenous diazepam therapy with regard to SE duration, intubation, or recurrent seizures in the emergency department. These data suggest that prehospital administration of diazepam may shorten the duration of SE in children and simplify the subsequent management of these patients in the emergency department.