The aim of the study was to detect significant biochemical changes in antioxidant status during acute period of ischemic stroke in its various pathogenic subtypes in patients aged 45–74years. The most important results were blood levels of ascorbic acid, malondialdehyde and free/ oxidized glutathione ratio. Cardioembolic stroke was associated with: the reduced ascorbic acid level of 62–74% comparable to control group; 5-times increased malondialdehyde level at the end of the first week of the disease; and also 50% decreasing of cell antioxidant capacity comparable to control group and other stroke subtypes. In lacunary stroke minimal changes in antioxidant status were measured, possibly because of small size of brain damage. Positive clinical dynamics was followed by decreasing of free glutathione levels. It could be related with its previous significant expenditure in process of cell recovery in penumbra area. In case of favorable outcome all of the markers return to the levels which were comparable to control group. The differences in the dynam-ics of the cells antioxidant capacity and consumption of native antioxidants, the time from the onset of the disease, the severity of the clinical picture, depending on the stroke subtype, were revealed. Further research of this problem may help to create new methods of diagnostics and selective pharmacological correction of this pathology.