In the present study, an effort was directed to assess the changes of hepatic ensymes according to the exposed in short and long surgical cases under halothane anesthesia. 60 surgical cases were studied in two different group. Halothane anesthesia was given for less than 2 hours in the first group of 30 cases and for more than 2 hours in the second group of 30 cases. The results were compared with the normal values and summarized as follows: In the first group, the changes after halothane exposure for less than 2 hours were negligible. In the second group, SGOT and SGPT were elevated significantly and the number of enzyme-elevated cases were 5~6 greater in group 1.