Thie study was conducted in the Anesthesiology Department of Chosun University Hospital from March to August 1987 using 0.5% isobaric bupivacaine and 0.4% hyperbaric bupivacaine as agents for spinal anesthesia. The following results were obtained. 1) The segmental heights and the highest level of sensory loss were significantly increased with increased dosage. In the hyperbaric bupivacaine groups of 15 mg and 20 mg respectively, the sensory lose in comparison with isobaric groups was significantly increased. 2) Less time was needed to achieve, complete motor blockade in the 15 mg hyperbaric bupivacaine group than in the isobaric groups but there were no significant differences between the other groups. The duration of motor blockade was more prolonged in the isdobaric bypivacaine groups using 15mg And 20 mg than in the hyperbaric groups. 3) The Group using 20 mg of hyperbaric bupivacaine demonstrated a significant decrease in blood pressure as coupared wish the group using 20 mg of isobaric bupivacaine. 4) Following spinal anesthesia, headache developed in 5 cases (5.6%). From the above results we conluded that isobaric bupivacaine and hyperbaric bupivacaine are appropriate anesthesia agents for surgery on the lower abdomen and lower extremities.