Halothane is usually a safe and effective inhalation anesthetic agent but it rarely has damaged liver. The authors selected 11 patients who had HBsAg positive and increased SGOT, SGPT at Yeungnam university hospital. Their physical status was ASA class 1 and 2. They had no previous history of operation or liver disease. The liver function tests were performed before surgery, and on 3rd, 7th and 10th postoperative days. The result were as follows: 1) The values of SGOT and SGPT were gradually increased on 3rd postoperative day and markedly increased on the 7th and 10th postoperative day. 2) Alkaline phosphatase, total protein, albumin, total bilirubin and direct bilirubin were not significantly changed.