BACKGROUND: This randomized, double-blinded clinical study was designed to evaluate the efficiency and safety of remifentanil with ketorolac for IV PCA after laparoscopic-assisted vaginal hysterectomy. METHODS: Eighty patients were randomly allocated into four groups. Group R received IV PCA using only remifentanil at a basal rate of 0.025 microg/kg/min and a bolus of 0.375 microg/kg. Group RK1 received IV PCA using remifentanil at a basal rate of 0.015 microg/kg/min and a bolus of 0.225 microg/kg. Group RK2 received IV PCA using remifentanil at a basal rate of 0.0075 microg/kg/min and a bolus of 0.1125 microg/kg. Group F received IV PCA using fentanyl at a basal rate of 0.3 microg/kg/h and a bolus of 0.075 microg/kg. In addition, ketorolac at a basal rate of 0.04 mg/kg/h and a bolus of 0.01 mg/kg was added to Group RK1, RK2, and F. All PCA conditions had a lock out period of 15 minutes. Pulse rate, systolic and diastolic BP, sedation score, visual analogue scale (VAS), and PONV score were recorded at 1, 3, 6, 12, and 24 hours after the operation. Total opioid use and the patients' number for rescue analgesic drug were also collected. RESULTS: The groups did not differ in PONV score and hemodynamic changes. The VAS in Group RK2 was high compared with the other groups. In addition, the sedation score was high in Group R. CONCLUSIONS: The additional ketorolac administration in remifentanil IV PCA had remifentanil sparing effects and reduced sedation among the side effects. Further studies will be needed to evaluate the precise and adequate dosage of ketorolac.