BACKGROUND: Ketorolac is a potent anlagesic drug which has anti-inflammatory action and this drug may decrease the needed amount of opioids when used together with them for postoperative pain control. Preemptive analgesia with these drugs is still controversial. The analgesic effect and the presence of preemptive analgesia of a nalbuphine-ketorolac combination were examined in upper abdominal surgical patients. METHODS: Thirty patients undergoing elective upper abdominal surgery were randomly allocated into two groups. Each group received 10 mg of nalbuphine as a bolus dose just before starting IV-PCA which contained nalbuphine 70 mg and ketorolac 150 mg in 88 ml of 5% dextrose water. Group I (n=15) received drugs before starting the operation and group II received them at the end of the operation. The basal rate, PCA dose and lock-out interval were 1.5 ml, 1.5 ml and 10 minutes, respectively. In each group, the postoperative visual analogue scale (VAS) score, degree of satisfaction, total amount of drug used and side effects were checked and compared with corresponding figures in the other group for two postoperative days. RESULTS: Postoperative pain after upper abdominal surgery was controlled well in all patients and there were no significant differences in VAS scores between the two groups. Most patients were satisfied with this regimen. There were no remarkable side effects. Preemptive analgesia of nalbuphine-ketorolac combination was not found. CONCLUSIONS: IV-PCA administration of nalbuphine 70 mg and ketorolac 150 mg combination is an effective method to control postoperative pain in upper abdominal surgical patients. Preemptive analgesia is not found with this regimen.