BACKGROUND: In children, fear of venipuncture and seperation from parents may produce stormy induction of anesthesia. Premedication administered by nontraumatic methods helps to decrease anxiety and minimize psychological trauma. METHODS: To define a dose of oral ketamine that would facilitate smooth induction of anesthesia for pediatric outpatient surgery without causing significant side effects, sixty children(ASA Physical Status 1; aged 1-7 years) undergoing inguinal herniorrhaphy were assigned randomly to four separate groups that received 5 mg/kg, 7 mg/kg, 10 mg/kg, or no ketamine(control group) mixed in 0.2 ml/kg cola. They were evaluated preoperatively and postoperatively for acceptance of oral ketamine, reaction to separation from their parents, acceptance of facial mask for inhalation induction, emergence delirium and postanesthetic complications. RESULTS: The 7 mg/kg and 10 mg/kg doses were well accepted; provided predictable sedation within 22-25 minutes; allowed calm seperation from parents and good induction conditions. However, the 10 mg/kg dose prolonged discharge time from recovery room, probably due to delayed recovery. Emergence deliriums were observed in two of all ketamine administered children(4.4%). And the incidences of postanesthetic complications such as vomiting, decreased appetite, lethargy, nausea, nightmare, behavioral change were slightly higher in ketamine administered groups, compared to the control group. CONCLUSION: The authors conclude that an oral dose of 7 mg/kg ketamine is well accepted in young children undergoing outpatient surgery for inguinal hernia and provides relatively predictable and satisfactory sedation without prolongation of discharge time and significant side effects.