Ketamine HC1(Phencyclidine derivative) is a white, crystalline substance with melting point 259℃. It is soluble in water to a 20% clear, colorless solution. a 10% aqueous solution has a pH 3.5. The chemical structure is 2-(O-chlorophenyl)-2-(methylamino) cyclohexanone hydrochloride. It is a rapid acting, nonhypnotic, nonbarbiturate drug with a wide safety margin. The author used the anesthetic ketamine hydrochloride for oral surgery procedure in 16 patients(2 to 33 years). Anesthesia was achieved with a single intramuscular injection by introduction of manufacture. Result obtained as follows : 1. It was easily administered. 2. Onset time was rapid and duration was short. 3. The mild cardiac stimulation resulted in moderate increase in the blood pressure and pulse. 4. There was no significant respiratory depression. 5. The airway can be maintained without artificial support or endotracheal intubation. 6. All protective reflex maintained, which was important in oral surgery. 7. The best results were achieved in pediatric patients than adults.