BACKGROUND In July 2013, the Department of Paediatric and Adolescent Medicine at Østfold Hospital Trust introduced nitrous oxide as an option for procedural sedation of children and adolescents. METHODS During the period 13 July 2013-25 August 2017, 311 procedures were performed with nitrous oxide in 238 patients aged 4-17 years. Age, sex, type and duration of procedure, any supplementary medications, complications and whether the procedure would previously have required general anaesthesia, were recorded in a form. The child rated the effectiveness of nitrous oxide using a graded age-appropriate 10-point pain scale, and the nurse rated it as good, moderate or none. RESULTS The children reported a median pain score of 2/10 (interquartile range 0-4), and nurses rated effectiveness as good in 247 of 304 (81 %) cases. For 43 % of procedures, the nurse felt that general anaesthesia would have been necessary had the department not had access to nitrous oxide. Adverse effects, most often dizziness, were reported in 110 of 311 procedures (35 %). In 7 of 311 procedures (2 %), the patient experienced adverse effects that resulted in stoppage of the procedure. The procedure was completed in 286 (92 %) children. CONCLUSIONS Nitrous oxide is a useful option for children who require procedural sedation, and means that more procedures can be performed without general anaesthesia.