Sedation of uncooperative children for dental treatment is difficult since treatment is mainly carried out inside the oral cavity. Dexmedetomidine (DEX), recently introduced into clinical practice, has little influence on respiratory system even at high doses. We present cases of patients who underwent dental treatment under sedation using DEX infusion. DEX at a dose of 1 microg/kg was administered over 10 min after intravenous cannulation. DEX was infused to maintain sedation level within the range of the Observer's Assessment of Alertness and Sedation (OAA/S) scale 3- 4 throughout dental treatments. They were successfully treated under DEX sedation without any complications. Their uncooperative behaviors were successfully managed under DEX sedation.