BACKGROUND: The new, long-acting local anesthetic ropivacaine is structurally very similar to bupivacaine, but the motor block is less profound and of shorter duration. The aim of this study was to compare analgesic effectiveness and side effects during postoperative pain control after a Caesarean section with either a bupivacaine/fentanyl or ropivacaine/fentanyl mixture. METHODS: Thirty-nine patients undergoing a Caesarean section were randomized in a double-blinded manner to receive bupivacaine or ropivacaine. Postoperative epidural analgesia was provided using a PCA pump with either bupivacaine/fentanyl 0.075%/3.4 microgram/ml after 10 ml of 0.125% bupivacaine with morphine (n = 18) or ropivacaine/fentanyl 0.125%/3.4 microgram/ml after 10 ml of 0.2% ropivacaine with morphine (n = 21). Verbal rating pain scores (rest and cough), side effects (nausea, vomiting, pruritus, sedation, motor block and hypotention) and time to ambulation were measured for 48 hr after surgery. RESULTS: There were no significant differences between the groups in verbal pain scores, sensory level, motor blockade and other side effects, but time to ambulation was earlier in the ropivacaine group. CONCLUSIONS: 0.125% ropivacaine with 3.4 microgram/ml fentanyl provided similar successful pain relief as 0.075% bupivacaine/fentanyl. However, earlier recovery of ambulation in patients receiving ropivacaine/ fentanyl will improve outcome after surgery.