Halothane is usually a safe and effective inhalation anesthetic agent but on occasion it has damaged and the blame put on other anesthetic agents. The author selected at random 33 patients who had had biliary system surgery at Wonju Christian Hospital between December 1983 to August 1984. Their physical status was ASA class l and ll, liver function tests were abnormal state and they had no previous history of operation or liver disease. They were divided into 4 groups according to the anesthetic agent used (halothane: 10, ebtrane: 10, Thalamonal neuroleptanesthesia:10, lidocaine epidural anesthesia:3) the liver function tests were performed before surgery, and on the 1st, 3rd, 5th and 7th postoperative days. The result were as follows: 1) Total protein, albumin, and total cholesterol were not significantly changed. 2) The values of SGOT gradually decreased in the Ethrane group and they were slightly increased on the first postop day in all 3 groups. The changes of the values were in the abnormal range. 3) The values of SGOT gradually decreased in the ethrane group and they were slightly increased on the first postop day in the halothane group. 4) The values of alkaline phosphatane, total bilirubin and direct bilirubin gradually decreased in the Ethrane group and the NLA group. They were slightly increased the first posopday in the halothane group and there was no significant change in the Epidural group. it is suggested that the influences of variable anesthetic agents on liver function is not significant in biliary system surgery with abnormal liver function.