BACKGROUND: The available data on the effect of dexmedetomidine premedication on anesthesia depth in children during general anesthesia are limited. This study was designed to determine the effect of preoperative dexmedetomidine administration on the bispectral index (BIS) and sevoflurane requirements in children during sevoflurane anesthesia. METHODS: 120 children aged 5 to 12 years undergoing concealed penis repair or hypospadias plastic surgery were randomized to receive preoperative administration of 0.25 µg kg RESULTS: Compared with those in Group C, the BIS values of children in Group D2 and Group D3 were significantly lower during sevoflurane induction and early maintenance (P <
0.017). Moreover, children in Group D2 and Group D3 had a lower ETsevo (P <
0.001) during sevoflurane maintenance than did those in Group C (P <
0.017). There were statistically significant differences in heart rate(P <
0.0001) and mean arterial pressure(P <
0.001) between the groups, but the incidence of bradycardia or hypotension was similar between the groups (p = 0.779 and p = 0.901). CONCLUSIONS: Children who received 0.5 µg kg TRAIL REGISTRATION: The trial is registered with the China Clinical Trials Registry Registration Number: ChiCTR1900026872. Date of registration: 10/24/2019.