We performed a retrospective chart review to determine the onset, duration, safety, and clinical sedative effects of 0.2 to 0.5 mg/kg intranasal midazolam in young children during laceration repair. Of 408 children treated for lacerations during an 8-month period, 42 (10%) received intranasal midazolam. Documentation was adequate for detailed analysis in 40 cases. Data are reported as mean +/- standard deviation and the frequency with 95% confidence limit (CL) estimates. The mean age of the study population was 32 +/- 9 months (range 12 months to 6 years), and the mean body mass was 14.5 +/- 3 kg. Topical or injected local anesthesia was used in 37 cases. Overall, 73% (CL 56% to 85%) of the children achieved adequate sedation. However, those receiving 0.2 to 0.29 mg/kg had adequate sedation in only 27% (CL 6% to 60%) of the cases compared with 80% (CL 52% to 95%) and 100% (CL 79% to 100%) when 0.3 to 0.39 and 0.4 to 0.5 mg/kg respectively were administered. When achieved, sedation occurred within 12 +/- 4 minutes, recovery occurred at 41 +/- 9 minutes, and discharge occurred at 56 +/- 11 minutes. No vomiting or clinically significant oxygen desaturation (defined as a drop of > 4% or to < 91%) was observed. We conclude that intranasal midazolam is a safe and effective sedative for laceration repair under local anesthesia in preschool-aged children. We recommend a dose of 0.3 to 0.5 mg/kg, with treatment failure less likely after 0.4 to 0.5 mg/kg compared with less than 0.3 mg/kg.