BACKGROUND: Intravenous patient-controlled analgesia (IV-PCA) has been widely used for pain relief after cesarean delivery under epidural anesthesia. However, IV-PCA alone has a limited effect on early postoperative pain relief. Epidural morphine injected intraoperatively could alleviate the early postcesarean pain. We evaluated the effects and side effects of intraoperative epidural morphine on postoperative IV-PCA. METHODS: Forty patients scheduled for cesarean section under epidural anesthesia were randomly assigned to one of two groups. The patients in the intravenous group (IV group, n = 20) received intravenous morphine 3 5 mg after the operation in the recovery room when patients complain of pain, and the patients in the epidural group (EPI group, n = 20) received intraoperative epidural morphine 3 mg after fetus delivery. After that, both groups received morphine IV-PCA (no basal infusion, bolus 1.0 mg, lock-out time 6 min). Analgesic efficacy, degree of patient satisfaction, drug consumption and side effects were compared at 4 and 24 hours after surgery. RESULTS: The EPI group had significantly lower VAS for pain at 4h after surgery on movement and resting than the IV group, whereas no significant difference was observed at 24h after surgery. The cumulative morphine consumptions at 4h and 24h after surgery were more in the IV group (each, P < 0.001). Fewer patients in the EPI group had drowsiness at 24h after surgery, but there were no significant differences in other side effects and degree of satisfaction between the two groups. CONCLUSIONS: We conclude that intraoperative epidural morphine was effective with less side effects for postoperative IV-PCA in the cesarean patients under epidural anesthesia.