BACKGROUND: Induced hypotension reduces blood loss in the surgical field and provides better visibility, but may produce an ischemic damage on liver. The purpose of this study is to evaluate postoperative liver function according to the degree of induced hypotension in spine surgery. METHODS: Sixty patients were classified into three groups. In group 1 (n=20) undergoing simple laminectomy, the systolic blood pressure (SBP) was maintained at 120 to 100 mmHg with controlling the concentration of enflurane. Hydralazine and/or esmolol were given to maintain the SBP at 100 to 80 mmHg in group 2 (n=20) and 80 to 60 mmHg in group 3 (n=20) as needed. Preoperative and postoperative 1, 3, 5, 7 day's serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) were evaluated. RESULTS: In group 1, postoperative SGOT levels were increased significantly on postoperative 1, 3, 5, 7 day and postoperative SGPT levels were increased significantly on postoperative 7 day only. In group 2, postoperative SGOT levels were increased significantly on postoperative 1, 3, 5, 7 day and there was no significant difference between preoperative and postoperative SGPT levels. In group 3, postoperative SGOT levels were increased significantly on postoperative 1, 3 day and postoperative SGPT levels were increased significantly on postoperative 3, 5, 7 day. There was no significant difference among three groups in SGOT and SGPT levels. Postoperative ALP levels were decreased on postoperative 1, 3, 5, 7 day in all groups and there was no significant difference among three groups except a significant difference between group 1 and 3 on postoperative 1, 3 day in ALP levels. CONCLUSIONS: These results suggest that severe reduction in SBP at 80 to 60 mmHg by hydralazine and/or esmolol under general anestheia with enflurane can not exclude the possibility of liver damage.