BACKGROUND: Lidocaine has been used for spinal anesthesia in short surgical procedure. However, transient neurologic symptoms (TNS) frequently occur after spinal anesthesia with lidocaine. Mepivacaine which has a silimar duration of action and rare incidence of TNS may be an alternative to lidocaine for spinal anesthesia. This study was designed to compare the efficacy of hyperbaric 1.5% lidocaine and 1.5% mepivacaine for spinal anesthesia. METHODS: Sixty patients, ASA physical status I or II, scheduled for lower abdominal or lower extremity procedures under spinal anesthesia were randomly allocated into two groups. Lidocaine group received 2% lidocaine 75 mg with 10% dextrose 1.25 ml. Mepivacaine group received 2% mepivacaine 75 mg with 10% dextrose 1.25 ml. After intrathecal injection of the anesthetics, sensorimotor block and recovery, cardiovascular effect and quality of surgical anesthesia were evaluated. TNS was evaluated 1 day after the operation. RESULTS: Both groups were similar with regard to demographic data and surgical procedures. The onset of sensory and motor blocks was similar in both groups. Time to regression to L5 sensory level and complete resolution of motor blockade were significantly prolonged in mepivacaine group than in lidocaine group (p<0.05). The effect of cardiovascular system was similar in both groups. Fentanyl was required for 4 cases only in the lidocaine group. None of both groups developed TNS. CONCLUSIONS: Hyperbaric 1.5% mepivacaine produced longer duration of action than hyperbaric 1.5% lidocaine in spinal anesthesia. This study didn't prove what drug develops a higher incidence of TNS.