Objective To evaluate the anesthetic efficacy of propofol used to supplement spinal anesthesia for sedation in the pediatric patients undergoing lower abdominal or lower extremity operations.Methods One hundred twenty pediatric patients of both sexes, aged 2-5 yr, weighing 11-21 kg, of ASA physical status Ⅰ or Ⅱ , scheduled for elective lower abdominal or lower extremity operations were randomly divided into 3 groups (n =40 each) using a random number table: general anesthesia group (group G), propofol used to supplement caudal block for sedation group (group PS+CB) , and propofol used to supplement spinal anesthesia for sedation group (group PS+SA).In group G, after induction of anesthesia, laryngeal mask airway was inserted, the patients were then mechanically ventilated, and anesthesia was maintained with iv infusion of propofol (5-7 mg· kg-1 · h-1), remifentanil (20-25 μg· kg-1 · h 1) and cisatracurium besylate (0.1 mg· kg-1 · h 1).In group PS+CB, caudal block was performed with the mixture 0.8 ml/kg of 1％ lidocaine and 0.25％ bupivacaine.In group PS+SA, spinal anesthesia was performed with isobaric bupivacaine 1.0 mg/age.Propofol was then infused at 3-5 mg · kg-1 · h-1 for sedation in PS+CB and PS+SA groups.Before anesthesia (baseline, T0) and at 1, 5 and 10 min after emergence from anesthesia (T1-3) , heart rate (HR), mean arterial pressure (MAP) and oxygen saturation (SpO2) were recorded.The emergence time, time for recovery of orientation, and duration of stay in postanesthesia care unit were recorded.Pain was assessed and scored, and agitation was graded at 5 min after emergence from anesthesia, and the occurrence of intraoperative traction reaction, body movement and nausea and vomiting within 24 h after operation was recorded.Results No intraoperative traction reaction and body movement was found in group PS+SA, and no patients stayed in postanesthesia care unit in PS+CB and PS+SA groups.HR and MAP were significantly higher at T1-3 than at T0 in group G (P＜0.05).Compare with group G, the HR, MAP at T1-3, pain scores, agitation scores, incidence of nausea and vomiting were significantly decreased, and the emergence time and time for recovery of orientation were shortened in groups PS+CB and PS+SA (P＜0.05).Conclusion Propofol used to supplement spinal anesthesia for sedation is effective and provides faster recovery from anesthesia with fewer complications in the pediatric patients undergoing lower abdominal or lower extremity operations.