Since ether was first introduced in Boston in 1846, many kinds of anesthetic techniques and agents have been developed. At the same time, there have been many controversies about the side effects following the use of anesthetic agents and they are studied actively by many investigators at the present time. The author chose 355 patients randomly who had received elective operation at the Pusan National University Hospital from October 1980 to March 1981 and made a study of their preand post-operative liver function test. The patients were divided into 3 groups and 214 the patients belonging to group l were anesthetized with general anesthesia and group 2 comprising 118 patients had spinal anesthesia and brachial plexus block was used in the group 3 of 23 patients. The results obtained were as follows: 1) The male to female ratio was about 3 to 2 (209 cases: 146 cases) and age distribution showed a range from 20 to 50 years(210 cases). 2) Pre-operative liver function test of group 1,2, and 3 proved to be abnormal in 75 cases, 23 cases, 6 cases respectively. 3) In patients of group 1, halothane alone(54 cases) and halothane with nitrous oxide(111 cases) were the most commonly used anesthetics. 4) Post-operative checkup of liver function test of 10 patients who were randomly selected from each group and who had previously had normal liver functions, 4 cases of group 1 turned out to be abnormal, but patients in group 2, and 3 showed no significant abnormality in the post-operative liver function test. 5) Anesthesia aggravated liver dysfunction of the patients of group l who had abnormal liver function prior to operation, but it returned to the pre-operative level within 10 days after operation.