BACKGROUND: Although degree of motor blockade during high thoracic spinal anesthesia is difficult to determine, pulmonary function may reflect the level of motor blockade. So we checked pulmonary function during spinal anesthesia with two different local anesthetic agents. METHODS: 50 patients, ASA PS 1-2, were randomly divided into two groups. After basal pulmonary function test (FVC: forced vital capacity, FEV1: forced expiratory volume in one second, PEFR: peak expiratory flow rate, PEP: peak expiratory pressure, PIP: peak inspiratory pressure.), the patients received spinal anesthesia with either 0.5% hyperbaric bupivacaine or 0.5% hyperbaric tetracaine. Thirty minutes after injection, level of sensory blockade was checked by pinprick test and pulmonary function test was performed. RESULTS: Almost all the values of pulmonary function reduced after spinal anesthesia, but the degrees of reduction were not differ in two groups except PEP, which reduced more profoundly in tetracaine group than bupivacaine group. CONCLUSIONS: It is more desirable that we use bupivacaine rather than tetracaine as spinal anesthetic agent in the patient with poor pulmonary function.