Background: Carotid endarterectomy (CEA) and carotid artery stenting (CAS) have both been proposed for treatment of critical atherosclerotic stenosis located at the carotid bifurcation. Monitoring of hyperintense microembolic signals (MES) by transcranial Doppler ultrasound (TCD) is considered a method of quality control, both in CEA and in CAS. Objective: To analyze temporal distribution of MES throughout both semi-eversion CEA and CAS procedures and to evaluate changes in mean velocity of blood flow through the ipsilateral middle cerebral artery (MCA). Method: Thirty-three procedures (17 CEA and 16 CAS) were prospectively monitored using TCD and the data were related to three different stages of surgery (pre-cerebral protection, during cerebral protection and post-cerebral protection). Chi-square, Mann-Whitney, ANOVA and contrast tests were used for statistical analysis. Results: The MES were uniformly distributed in the CEA group, but not in the CAS group (p = 0.208). The number of MES was higher in the CAS group in all stages. The average flow in the MCA was similarly lower in both groups during the protection stage. Conclusion: CEA provoked a lower incidence of MES per procedure than CAS in all stages. The behavior of the averages of the mean of blood flow through the MCA was similar in both groups. © 2016, Sociedade Brasileira de Angiologia e Cirurgia Vascular. All rights reserved.153197204