Abstract: Objective To evaluate the blocking characteristics of epidural volume extension on combined spinal-anesthesia of parturients undergoing cesarean delivery. Methods Eighty parturients were randomly allocated to one of four groups, receiving 0, 5, 10 or 15 mL normal saline, respectively, through epidural catheter at a rate of 0.5 mL/s (n=20 in each group) after combined spinal-anesthesia with 11 mg intrathecally isobaric bupivacaine. Peak sensory block height, time for sensory block to sixth thoracicdermatome level, time for highest modified Bromage motor score, time for sensory regression to tenth thoracicdermatome level, and motor block recovery to Modified Bromage 0 were recorded. Results The groups with 10 mL and 15 mL epidural extension had a higher level of peak sensory and shorter time for the sensory block to sixth thoracicdermatome level compared with the control group ( P<0.05). There were no significant group differences in the time for sensory regression to tenth thoracicdermatome level ( P>0.05). The saline epidural extension groups had significant shorter time for highest modified Bromage motor score and motor block recovery to Modified Bromage 0 compared with the control group ( P<0.05). The use of phenylephrine was significantly higher in the 15 mL treatment group ( P<0.05). Conclusion 10 mL of epidural saline volume extension is optimal for combined spinal-epidural anaesthesia of parturients undergoing caesarean delivery.