Surgery and manipulations performed with stenotic lesions of the cerebral arteries, along with antithrombotic and lipid-lowering therapy, are the basis of primary and secondary prevention of ischemic stroke, but can be the source of perioperative embolism in the cerebral arteries. Determine the composition of the embolic material and the clinical significance of microembolus identified in the cerebral vascular bed during carotid endarterectomy and carotid stenting. A total of 41 patients with hemodynamically significant stenosis of the left/right ICA, who were treated at the hospital from 2013 to 2015 (26 patients were operated by the method of endarterectomy, 15 patients - by the carotid stenting method). MES registration was performed intraoperatively for each patient by the method of bilateral Doppler monitoring of MCA on the SOMOMED-300M device. It was established that the total number of registered cerebral MES significantly predominates during endovascular interventions due to massive gas embolism. The number of material microparticles prevails in patients undergoing endarterectomy compared with carotid stenting. Most of the material microparticles (up to 80%) when performing carotid stenting are recorded at the stage of stent implantation and subsequent deflation. The majority of material emboli (up to 62%) during endarterectomy were recorded before the internal carotid artery was clamped, at the stage of atherosclerotic plaque isolation. The critical stages of registration of MES of material origin are: for carotid stenting, the stage of stent implantation with subsequent deflation; for endarterectomy, the stage of atherosclerotic plaque isolation to the clamping of the internal carotid artery.