The aim of this study was to determine the effects of an acute decrease in serum estrogen concentration on endothelial function in women with surgically induced menopause through the use of color Doppler ultrasonography. There were 40 women scheduled to undergo total abdominal hysterectomy and bilateral salpingo-oopherectomy who participated in the study; 15 women not undergoing surgery also participated as a control group. Color Doppler ultrasonographic examinations of each surgical patient were obtained 3 days prior to and 7 days after surgery. Baseline measurements of the brachial arteries, including peak systolic velocity, end-diastolic velocity, true mean velocity, arterial diameter, and volume flow, were obtained for each patient. After baseline measurements were established, hyperemia was induced by inflating a blood pressure cuff on each patient's upper arm to suprasystolic pressures for 5 min. To evaluate endothelium-dependent vasodilation, the ultrasonographic appearance of the brachial artery was evaluated after the cuff was deflated and removed from the arm. Measurements of peak systolic velocity, end-diastolic velocity, true mean velocity, arterial diameter, and volume flow were obtained, and were repeated at 1, 3, 5, 10, and 20 min subsequent to removal of the blood pressure cuff. The differences between baseline and maximum values of each Doppler parameter after the cuff deflation were calculated. No significant differences were identified in terms of laboratory findings or systolic and diastolic pressures in pre- and postoperative status of surgical patients, or between surgical patients and the control group. A significant difference in serum estradiol levels during pre- and postoperative periods ( P<0.001) was detected. No significant difference in serum estradiol levels was detected among preoperative surgical patients and members of the control group ( P=0.72). All net changes detected within each group during reactive hyperemia were statistically significant. No significant difference in values was detected among pre-, postoperative, and control subjects. Our study reveals that acute decrease in serum estrogen level does not appear to affect endothelial function; thus, we assume that this is mainly due to the result of postoperative surgical stress.