Epidural analgesia is the most efficient technique for labor pain relief. However, its resultant motor block might impair the mode of delivery, particularly in breech presentation where the risk of dystocia is high. In this trial, we compared bupivacaine 0.125% with a combination of a low concentration of bupivacaine (0.0625%) and sufentanil (0.25 microg.mL(-1)) both administered by continuous infusion. Analgesia, maternal and fetal/neonatal side effects and obstetric outcome were compared between group bupivacaine (n = 23) and group bupivacaine-sufentanil (n = 35). A greater number of patients in the bupivacaine 0.125% group required more than two top-ups (32 vs. 8% of patients, P = 0.03) while pain scores were similar. Motor block at delivery was more pronounced in the bupivacaine 0.125% group. Nausea and pruritus were more often encountered in the bupivacaine-sufentanil group. There was a trend toward a decreased rate of assisted or operative delivery in the bupivacaine-sufentanil group (92% vs. 74%, P = 0.09). Fetal/neonatal data did not differ between groups. Epidural analgesia with bupivacaine-sufentanil required fewer additional top-ups and produced less motor block than did bupivacaine 0.125%. However, there was no significant difference in mode of delivery between the two analgesic regimens.