Objectives: Etiology of ischemic stroke(IS) remains sometimes unexplained in younger subjects. Its well-known causes are atherosclerosis(AS), embolization, arterial dissection, congenital defects, vasculitides, smoking, use of oral contraceptives, coagulopathy and arterial dissection, or vasospasm.Case report: A 54-year old male subject was examined because of motor disturbance in his left upper extremity. Computerized tomography(CT) of the brain did not detect any focal pathological changes. Utrasonographic(USG) examination revealed severe stenosis of the right internal carotid artery(ICA) caused by hypoechogenic material, the blood velocity beyond the stenosis was 240 cm/s. The USG finding was confirmed by digital subtraction angiography (DSA). Based on the results of these examinations, an acute carotid endarterectomy (CEA) was indicated. During CEA the vascular surgeon observed patency of the ICA with only small calcified AS plaque on its posterior side. Ultrasonographic examination, performed on the 5 th day, showed a small calcified AS plaque on the posterior side of the right ICA. Conclusion:In conclusion, if we exclude the possibility of a false positivity of 2 imaging methods at once, we have encountered a very unusual case of SR of stenosing material in the extracranial part of the ICA, initially causing its severe stenosis manifesting by acute neurological symptomatology. The mechanism of this SR remains unclear and the problem should be further studied, preferably using less invasive AG methods.