In order to determine the efficiency of intranasal midazolam in prolonged convulsive episodes, we conducted a prospective study in children with various types of seizures. Nine patients (six boys, three girls; age range 6 months to 9 years) with prolonged convulsions lasting more than 10 min were treated with intranasal midazolam, 0.3 mg/kg. The success rate was 100% with only one case requiring a second dose. Estimated duration of seizures was 12-30 min (mean 18.6) while mean time elapsed until cessation of seizures was 139.6 s (range 60-480). No significant adverse effects were noted except for one patient who had seizures secondary to serious CNS infection and respiratory depression after intranasal midazolam.