The purpose of this study was to assess the sedative effect of three kinds of medication for management of the uncooperative 60 children aged from 16 months to 87 months required extensive treatment. The patients were given randomly a dose of 75mg/kg of chloral hydrate and hydroxyzine 25mg orally or 0.5mg/kg of midazolam orally or 0.3mg/kg of midazolam intranasally. All the children were restrained in a Pediwrap and were monitored with Pulse oximeter for assessing the safety of patients. According to rating scale, sleep, crying, movement, and overall behavior were checked for evaluation of the clinical sedative effect. The results were as follows: 1. In the evaluation of sleep, rating scale of chloral hydrate/hydroxyzine was superior to the other group(p<0.05). 2. In the evaluation of crying and movement at beginning of treatment, rating scale of chloral hydrate/hydroxyzine was superior to the other group(p<0.05), but during the treatment, rating scale of each group was not significantly different (p>0.05). 3. In the evaluation of overall behavior, 80% children of chloral hydrate/hydroxyzine were rated good or very good. With the oral and intranasal midazolam, 60% children were rated good or very good respectively. 4. There were no clinical signs of significant cyanosis and respiratory depression. Clinically, chloral hydrate/hydroxyzine was proved to be more effective sedation than any other sedative method. Oral and intranasal midazolam were also safe and effective sedation in young children undergoing pediatric dental procedures.