['To establish the S-100beta protein profile during carotid artery surgery to show a possible correlation between postoperative stroke and this biochemical marker.', 'Prospective, nonrandomized study.', 'Departments of anesthesiology, biochemistry, and vascular surgery in a single university hospital.', 'One hundred patients consecutively scheduled for carotid endarterectomy.', 'Postoperative neurologic complications were defined as major, occurrence of a postoperative permanent stroke, or minor, occurrence of a new postoperative transient ischemic attack lasting < 2 hours. Serum samples were obtained before induction, before carotid artery cross-clamping, after declamping, at the end of surgery, during recovery, and on the first postoperative day. Concentrations of S-100beta were analyzed using a commercially available kit (LIA-mat S300 analyzer, Byk-Sangtec Medical, Bromma, Sweden). Ninety-five patients awoke without a neurologic defect. Three patients experienced a permanent stroke, and 2 patients had a transient ischemic attack. S-100 basal values were unrelated to preoperative status, including hypertension, neurologic status, renal function, and degree of the carotid lesion. S-100 concentration increased slightly but significantly at the end of surgery and remained stable until the first postoperative day. S-100 profile during the procedure was independent of the duration of carotid artery cross-clamping and the need for a shunt. S-100 serum level was not significantly different in the patients with a postoperative ischemic event in comparison with the entire group. The S-100 profile was not increased in 2 of 3 patients with a permanent stroke and in 1 of 2 patients with a transient ischemic attack in comparison with the 95 patients with uneventful recovery.'] Do s-100beta protein levels correlate with stroke in patients undergoing carotid endarterectomy under general anesthesia?