BACKGROUND: Epidural administration of local anesthetics and opiate or intravenous administration of opiate and ketorolac has proven to be effective in the treatment of postoperative pain. Studies that compare epidual morphine-bupivacaine vs intravenous nalbuphine-ketorolac administration showed conflicting results. We compared the ability and side effects of epidural (EPI-PCA) morphine-bupivacaine versus intravenous (IV-PCA) nalbuphine-ketorolac for postoperative pain relief after cesarean delivery. METHOD: Sixty healthy women were randomly assigned to receive an epidural bolus of morphine 3 mg mixed with 0.5% bupivacaine 10 ml, followed by a EPI-PCA with 0.0125% morphine and 0.125% bupivacaine (basal infusion 2 ml/hr, bolus 0.5 ml, lock-out interval 15 min) or intravenous bolus of nalbuphine 5 mg, followed by a IV-PCA with 0.05% nalbuphine and 0.15% ketorolac (basal infusion 2 ml/hr, bolus 0.5 ml, lock-out interval 30 min) for pain relief after cesarean delivery. The intensity of pain was assessed by the patient, who was unawared of the dose given, using a visual analog scale (VAS). To compare intensity of pain, VAS was used at 1, 6, 12, 24 and 40 hour after the end of surgery. RESULT : EPI-PCA group had significant lower visual analog scale (VAS) at immediate postoperative period, whereas no significant difference was observed when pain was assessed at other time sequence. Pruritus was more frequent with EPI-PCA group, although the incidence of other side effects were the same. CONCLUSION: We conclude that EPI-PCA or IV-PCA using morphine-bupivacaine or nalbuphine- ketorolac is relatively effective and safe method for the postoperative pain control. Although EPI-PCA with morphine-bupivacaine shows lower VAS at immediate postoperative period, IV-PCA with nalbuphine-ketorolac is a safe and effective alternative to EPI-PCA with morphine-bupivacaine for providing pain relief after cesarean delivery.