The presence of a bruit after carotid endarterectomy may indicate a persistent or recurrent lesion. The authors noninvasively evaluated, by Duplex scanning, 18 asymptomatic postoperative patients who underwent a total of 23 carotid endarterectomies and who developed a postoperative bruit to determine the significance of the bruit. Eleven men and seven women were studied from 6 weeks to 2 years postsurgery. Ages ranged from 49 to 75 years (63.6 +/- 8.0 years). Indications for endarterectomy were: transient ischemic attacks (including amaurosis fugax), 17 vessels; completed stroke with significant functional recovery and residual carotid disease, 3 vessels; and asymptomatic bruit with hemodynamically significant carotid stenosis, 3 vessels. Each patient had a Duplex scan performed to noninvasively evaluate the carotid artery. All scans were independently reviewed by two observers. Real-time B images were interpreted as normal in 14 vessels, mild thickening in eight vessels, and moderate thickening in only one vessel. Doppler recordings demonstrated a spectral range of 15-40 cm/sec (26 +/- 8 cm/sec). Ratio of velocity in the internal carotid artery to common carotid artery (VIC/VCC) ranged from 0.389 to 1.281 (0.779 +/- 0.250). This study demonstrates that the presence of a postoperative carotid bruit does not necessarily signify the presence of residual carotid disease or a hemodynamically significant lesion.