BACKGROUND: This study aimed to compare analgesic efficacy and occurance of motor block and other side effects of a 48 hr postoperative continuous epidural infusion of 0.125% bupivacaine or ropivacaine with morphine. METHODS: Forty patients undergoing a Cesarean section were allocated randomly into two groups. Both groups received an epidural injection of 2.0% lidocaine 18 20 ml and 0.5% bupivacaine 2 5 ml with fentanyl 50microgram 20 minutes before surgical incision and received 2 mg of epidural morphine by bolus 40 minutes after surgical incision. For post-operative pain control, a continuous epidural infusion was started using a two day infusor containing 6 mg of morphine in 100 ml of 0.125% bupivacaine (Group 1, n = 20) or 100 ml of 0.125% ropivacaine (Group 2, n = 20). Visual analog scale (VAS) for pain during rest and movement, sensory change and motor blockade were assessed for 48 hrs. after surgery. RESULTS: There were no significant differences in VAS for pain during rest and movement. The incidences of side effect were similar in both groups. CONCLUSIONS: Using 0.125% bupivacaine with morphine via the epidural route provided similar pain relief and side effects as 0.125% ropivacaine with morphine.