It is one of difficulties to control children who show definitely negative behavior in dental clinic. In such a case, the pharmacologic management has been used to provide quality care, minimize the extremes of disruptive behavior, promote a positive psychologic response to treatment and patient welfare and safety. Deep sedation can be defined as a controlled, pharmacologically-induced state of depressed consciousness from which the patient is not easily aroused which may be accompanied by a partial loss of protective reflexes. In this retrospective report, the sedation records of 200 pediatric dental patients of ASA Class I & II who were not successfully treated under conscious sedation were used for analysis. Most frequently used regimen of deep sedation was the co-medication of midazolam(0.3mg/kg), enflurane(1.0-2.0 vol%) and 50-70% $N_2O_2$. The average age and weight of the patients was 4.6 yr (S.D: 2.72) and 18.7kg(S.D: 6.35) respectively. The average operative time was 52 minutes and midazolam (0.1-0.2cc) was additionally administered intranasally to prolong the operative time as needed. The episodes of untoward side effects were reported during and/or after the procedure in 58 patients. Serious adverse reactions such as cyanosis or laryngospasm were even reported in 7 patients but without mortality. Deep sedation is a very effective way of completing the dental treatments for those who failed to respond well to the conscious sedation. This technique has many practical advantages over general anesthesia case but the demands for the rigid monitoring criteria limit its use in general practice setting. The continuous efforts to improve the safety of the medication and the technique are required for the benefits of the patients and parent.