The study deals with cerebral tissue stupefiation ph enomenon caused by internal carotid artery stenosis before and after endarterectomy. Carotid endarterectomy was performed in 50 patients who underwent ischemic stroke, selected based on NaSCeT criteria, after conventional hours of therapeutic window expiration. Following methods were used: neurological examination with sistematization of data according to Barthel and ashworth indexes, to Fugl Meyer scale, superior and inferior rivermed scale, investigations (cerebral CT and MrI), carotid vessels’ doppler examination, carotid angiography. Carotid endarterectomy was initially a secondary stroke prevention method, proved to be a good treatment option as well (significant improvement of disability degree in patients who underwent ischemic stroke). Study results lead to the conclusion that ischemic cerebral tissue preserves recovery capacity after conventional hours of therapeutical window (stupefiation phenomenon of ischemic cerebral tissue). Th is is the etiopathogenetic basis of cerebral tissue preconditioning phenomenon, largely described in contemporary scientific medical literature (animal models).