BACKGROUND: The effect of epidural local anesthetics on the spinal anesthesia is not well known during the combined spinal epidural anesthesia (CSE). But, Blumgart and his colleagues suggested that epidural volume load affect spinal sensory blockade level. This study was designed to investigate the effect of extradural injection of normal saline on the level of the subarachnoid block according to the time of the extradural saline injection. METHODS: Sixty patients undergoing lower abdominal and lower extremity operation were involved in our study. After performing subarachnoid block with 12 mg of hyperbaric tetracaine, divided into as follows: Group 1 (n=20), received only spinal anesthesia; Group 2 (n=20), received 15 ml of epidural saline immediately after spinal anesthetic administration; Group 3 (n=20), received 15 ml of epidural saline at 15 minutes after spinal anesthetic administration. Sensory blockade level was checked by pinprick test at 5, 10, 15, 20, 25, 30, 40, 60 and 90 minutes. Blood pressure, heart rate and incidence of complications such as hypotension, bradycardia, nausea and high spinal block were also measured. RESULTS: The maximal sensory blockade level of Group 2 was higher than those of Group 1 and Group 3 (p<0.05). However, there was no difference between Group 1 and Group 3 as comparing to the maximal sensory blockade level. Changes of blood pressure and heart rate and incidence of complications were not different comparing with each other groups (p>0.05). CONCLUSIONS: From the results obtained, epidural volume load at the 15 minutes after spinal anesthetic administration did not affect the sensory blockade level of spinal anesthesia during CSE.