Background: This study was aimed to compare the analgesic effect and side effects of morphine- bupivacaine mixture with those of fentanyl-bupivacaine mixture after Cesarean section. Methods: Eighty patients who were taken continuous epidural catheterization after Cesarean section were divided into two groups. In group 1 (N=40) the mixture of 1% lidocaine 10 ml and morphine 1mg was firstly injected via epidural catheter, and then two day infusor (Baxter(R)) which contained the mixture of 0.15% bupivacaine 100 ml and morphine 6mg was connected to epidural catheter. In group 2 (N=40) the mixture of 1% lidocaine 10 ml and fentanyl 100 mcg was firstly injected via epidural catheter, and then two day infusor (Baxter(R)) which contained the mixture of 0.15% bupivacaine 100 ml and fentanyl 850 mcg was connected to epidural catheter. Mean arterial pressure (MAP) and heart rate (HR) were checked preoperatively, and at post-injection 10, 20, 30 and 60 minutes. The visual analogue scale (VAS) was checked at postoperative 1/2, 1, 6, 12, 24 and 48 hours. The side effects of epidural analgesia were evaluated. Results: In group 2 MAP was significantly decreased at post-injection 20 minute. VAS was significantly increased at post-injection 1/2 and 1 hour in group 1. The most frequent side effect was pruritus in both groups. Conclusions: The first bolus injection of the mixture of 1% lidocaine 10 ml and fentanyl 100 mcg has more rapid analgegic effect than the mixture of 1% lidocaine 10 ml and morphine 2 mg, but because of shorter duration of action of fentanyl it seems to be better to increase the dosage of fentanyl or replace fentanyl by morphine for more effective epidural analgesia after Cesarean section.