The aim of this research was to investigate the influence of intracranial stenoses or occlusions on the outcome of carotid endarterectomy (CEA) in patients with internal carotid artery stenosis. The authors also searched for internal carotid artery plaque's morphology influence on the atherosclerotic process in intracranial arteries. The study included 154 patients who underwent angiography and CEA. Intracranial lesions (stenosis or occlusion) were stated in 28 (18.2%) patients. Perioperative stroke - death rate was 3.9%. Statistical analysis revealed that perioperative stroke after CEA appeared significantly more often in patients with intracranial stenoses or occlusions (p = 0.0104). Late death-stroke rate was 13.6%. Log-rank test revealed that after a 1-year follow-up period, there were significantly more survivals in patients without intracranial lesions than in those with intracranial lesions (p = 0.048). Intracranial stenosis or occlusion predicts poor perioperative neurological outcome. Patients with intracranial lesions benefit less from endarterectomy in a 1-year follow-up period. On the basis of internal carotid artery plaque's morphology, no conclusions on advancement of intracranial arteries' atherosclerosis can be made.