Nitrous oxide is an inhaled agent commonly used by dental staff to provide anxiolysis and analgesia for dental procedures and by anesthesia personnel as an adjunct to more potent general anesthetic gases. More recently, nitrous oxide has been used to provide sedation/analgesia for a variety of medical procedures in children outside of the operating room, including lumbar puncture, laceration repair, fracture reduction, and urologic imaging. We report 3 cases of clinical seizure activity associated with nitrous oxide administration for pediatric procedural sedation. Although temporally related, no causality is established. Review of the medical and dental literature confirm the rarity of these events.