Nitrous oxide has been widely employed by dentists as an anesthetic agent throughout its history of clinical use. While hypoxic general anesthetic techniques using nitrous oxide are rarely if ever employed today in the United States, and appear to be on the decline abroad, nitrous oxide is extensively and successfully used in dentistry as a conscious sedative to reduce anxiety and provide some supplemental analgesia. Less frequently it is used as a co-agent with intravenous anesthetics or sedatives during oral surgery or restorative dentistry. Considering the number of patients given this agent on a yearly basis, its relative lack of reported side effects when used appropriately is remarkable.