Background: We compared butorphanol and fentanyl for opioids use in patient-controlled analgesia(PCA) with ketorolac to determine a suitable drug combination for postoperative pain control. Methods: Sixty patients were equally divided into 2 Groups. Group 1 (n=30) butorphanol 10 mg with ketorolac 180 mg; Group 2 (n=30) fentanyl 1 mg with ketorolac 180 mg, diluting 100 ml solutions intravenously via PCA pump after total abdominal hysterectomy under general anesthesia. Total infusion dosage of PCA drug, VAS pain scores, and side effects of both group were manitored. Results: Total infusion dosages were as follows: (Group 1) butorphanol 8.3 mg with ketorolac 149.7 mg; (Group 2) fentanyl $646.6;{mu}g$ with ketorolac 116.2 mg. The two groups showed similar pain scores auld side effects. Conclusions : Both butorphanol and fentanyl were effective for postoperative pain control using PCA pump, but butorphanol was more economical. The putative potency ratio of butorphanol to fantanyl was 12.8 : 1.