OBJECTIVE:To study the effect of N(2)O inhalation and propofol intravenous anaesthesia in tooth extraction. METHODS: 40 dental outpatients with the extraction of the mandibular wisdom tooth,ASAI,were randomly allocated to two groups:N(2)O group with the age of 20-36 years old and propofol group with the age of 21-35 years old.All cases undergoing dental extraction were given ultra-light anaesthesia as an adjunct local anaesthesia. RESULTS: The two groups were gained various levels of sedation,there were no significant difference among BP,HR,RR,SPO(2) before,in,and after the operation.Dental treatment could be carried out in cooperating conditin throughout the whole procedure.There was a certain extent of amnesia postoperation,the incidence of postoperative side effects was low,the recovery time was gained within 30 minutes. CONCLUSION: The analgesic effects of N(2)O group were superior to the propofol group.