Background: Carotid artery stenting (CAS) is associated with the risk of intraprocedural stroke. A better understanding of specific risk factors could help to improve the procedure and to reduce the overall risk of CAS. We addressed the role of carotid plaque echolucency as potential risk factor for cerebral embolism during CAS. Methods: We prospectively evaluated carotid plaque echolucency by use of a computer-assisted measure of echogenicity, the gray scale median (GSM), in 31 consecutive patients with symptomatic high-grade carotid stenosis that were scheduled to undergo CAS. Dual-frequency transcranial Doppler ultrasound was used to detect solid cerebral microemboli during CAS. Results: 27 of the 31 patients met all inclusion/exclusion criteria.Solid cerebral microemboli were detected during 17 of 27 CAS procedures. The GSM of the target plaques was lower in subjects with intraprocedural embolism (37.9 ± 20.8) than in those without (58.2 ± 25.7) (p = 0.040). A receiver-operating characteristic analysis showed that the GSM that gave the greatest separation between plaques with a higher and a lower probability of intraprocedural embolism was 50: the proportion of subjects with intraprocedural embolism was 85% in CAS of echolucent plaques (GSM <50) and 42% in CAS of echogenic plaques (GSM ≥50) (p = 0.031). Conclusions: CAS of both echolucent and echogenic carotid plaques may be associated with cerebral embolism, particularly CAS of echolucent plaques. Plaque echolucency alone does not reliably identify patients at particularly high risk of intraprocedural embolism, but should be considered as one of a broad panel of risk factors of CAS.