Background and purpose: Ischemic stroke is one of the most important diseases causing severe disability and death. Hypertension is the most important risk factor in strokes, representing roughly 70% of all cases. Oxidative stress plays an important role in acute ischemic stroke (AIS) pathogenesis. It is believed to be one of the mechanisms taking part in neuronal damage in stroke. Free radical formation and subsequent oxidative damage may be a factor in stroke severity. In 28 patients with AIS and 28 healthy individuals were investigated with regard to relationship between ischemic-stroke and glutathione peroxidase (GSH-Px), catalase (CAT) activities, malondialdehyde (MDA), glutathione, beta-carotene, vitamin A levels.