This study was designed to compare the effect of combined spinal epidural anesthesia (CSEA) and spinal anesthesia on the incidence and severity of hypotension of patients undergone cesarean section. Sixty term parturients, ASA class I-II were randomly divided into two groups. Regional anesthesia was performed in right lateral, horizontal plane position. In Group 1, spinal group, 2.0-2.5 ml. of 0.5% hyperbaric bupivacaine was given intrathecally. In Group 2, CSE group, 1.5-2.0 ml of 0.5% hyperbaric bupivacaine was given intrathecally and epidural lidocaine would be added if analgesic level was lower than T4 at 15 minutes after intrathecal injection or inadequate analgesia occurred during surgery. There were no significant differences in the incidence and severity of maternal hypotension, ephedrine requirement, maximal cephalad level of analgesia and analgesic level at 15 minutes after intrathecal injection between the two groups. CSEA in right lateral, horizontal plane position has no advantages in term of maternal hypotension during cesarean section as compared to spinal anesthesia.