Dental treatment of mentally challenged patients under general anesthesia is a series of challenging procedures not only for dental operators but also for dental anesthesiologists. Patients presenting with uncooperative behavior often resist the perioperative management for adesthestic administration. This case report suggests oral premedication as a conjuctive method for anestheitic induction. A 26-year-old male dental patient with autism was referred to dental treatment under general anesthesia. The patient refused to enter dental clinic office and was not able to receive preoperative assessment. In the day of operation, 15 mg of midazolam was given to the patient for oral premedication prior to anesthetic induction. Ater 20 minutes, the patient presented with drowziness and was transferred to the office. Anesthestic staff were able to achieve appropriate intravenous access and mask inhalation. The patient recieved 8 hrs long dental treatment and recovered in a noncomplicated way. Oral midazolam is commonly used to reduce anxiety for combative and irritated pateints. In this case, oral midazolam sedation was used as a preanesthetic management of a highly uncoopearive patient.