BACKGROUND: Induced hypotension reduces blood loss in the surgical field and provies better visibility. May methods have been used for induced hypotension. Recently Esmolol is favored in induced hypotension because of its short action of sympathetic beta-1 receptor antagonist and easy to control. Thoracic epidural bldegrees Ck can provide cadiovascular stability in induced hypotension. The purpose of the study is to compare postoperative liver function after induced hypotension between thoracic epidural bldegrees Ckade and esmolol combined with general anesthesia with isoflulane. METHOD: Fourty patients scheduled for spinal posterior fusion under general anesthesia were randomly divided into two groups. In thoracic epidural bldegrees Ckade group(Group I, 20 patients), 8~10 ml of 2% liddegrees Caine was injected into the epidural catheter ldegrees Cated in T6~7 interspace in a bolus. In Esmolol group(Group II, 20 patients) received 0.5 mg/kg as loading dose and 50~150 microgram/kg/min continuously. We measured preoperative and postoperative 1, 3, 5, 7 day's serum glutamic-oxaloacetic transaminase(SGOT), serum glutamic-pyruvate transaminase(SGPT) and alkaline phosphatase(ALP). RESULT: In the thoracic epidural bldegrees Ckade group, there was statistically significant increase of SGOT level above normal range on postoperative 1 day, which decreased on postoperative 3 and 5 day(p<0.05). But it was within normal range on postoperative 7 day. SGPT was increased within normal range. Similarly, in the esmolol group, there was statistically significant increase of SGOT level above normal range on postoperative 1 day, which decreased on postoperative 3 and 5 day(p<0.05). But it was within normal range on postoperative 7 day. SGPT was increased within normal range. The level of ALP was increased within normal range in both groups. There was no statistically significant difference in liver function between two groups. CONCLUSION: We consider that postoperative liver function is little influenced with induced hypotension by thoracic epidural bldegrees Ckade and esmolol combined with general anesthesia with isoflurane.