We evaluated the influence of epidural and spinal anesthesia on VO2 and VCO2 measured by the indirect calorimetry. According to the spreading of anesthetic level, VO2, VCO2 and EE increased in the epidural group (EP group), but they decreased in spinal group (SP group). RQ was unchanged in both groups. Rate pressure product (RPP), in proportion to the MVO2 and the REE, did not correlate with the EE. The VO2, VCO2 and EE in EP group increased probably because; (1) epidural anesthesia does not affect the VO2 change, as it does not markedly suppress respiration; (2) cardiac stroke work is retained during epidural anesthesia, as it does markedly suppress circulation. In conclusion, epidural anesthesia exerts less influence on the respiratory and circulatory systems of patients compared with spinal anesthesia.