The influences of endothracheal anesthesia upon the liver function in the preoprative stage, during the operation and after the recovery was estimated measuring the serum bilirubin and BSP test and the results in both groups were compared. 1) The total serum bilirubin increased in both groups slightly during the opeartion and mostly after the recovery. It showed a tendency to decrease gradually at the third postoperative day. But its mean value was larger in the hypotensive group than in the normal group during the operation. After the operation, however, it was rather more in the normal group. 2) The increase of the total serum bilirubin during the operation was mostly dut to the increase of the direct and indirect bilirubin. 3) BSP-test during the operation showed an increase of 22.5%-25.7% in the blood, but it showed a marked restoratation after recovery in both groups. BSP in the blood of the normal group during the operation seemed more than that of the hypotensive group, but not different after recovery.