Background : Autonomic reflex dysfunction in patients with diabetes is associated with unstable cardiovascular response in perioperative period. In this study we wanted to investigate the extent to which the intraoperative cardiovascular responses depend on the degree of autonomic dysfunction. Methods : The influence of diabetic autonomic neuropathy upon the behavior of the circulatory system was investigated in 35 patients who had undergone ophthalmological surgery. A standardized test combination was used to study the patient's cardiovascular refractory reactions. The patients were then divided into a control group, non-diabetics without autonomic neuropathy (n = 18), and an experimental group, diabetics with autonomic neuropathy (n = 17). The anesthetic and surgical procedures (vitrectomy) were standardized and always identical. Results : During the induction of anesthesia, patients in the experimental group didn't experience changes in mean arterial blood pressure and heart rate as compared to patients in control group. During the maintenance of anesthesia, there were significant decreases in mean arterial blood pressure and heart rate in the experimental group, but in the state of emergence of anesthesia, there were no significant differences in either group. Conclusions : Autonomic neuropathy represents a perioperative risk factor, especially during induction and maintenance of anesthesia. I therefore recommend an autonomic nervous function test for evaluation of diabetic autonomic neuropathy in preoperative anesthesiological examination. (Korean J Anesthesiol 1999; 37: 1034∼1040)