A condition of oxidative stress is known to occur in ischemic stroke, the current therapeutic intervention of which is largely limited to thrombolysis. To assess the effect of vitamin C – in conjunction to aspirin – in ischemic stroke-related lipid peroxidation, we measured plasma levels of ascorbate, of 8,12-isoprostanes F_{2α}-VI (8,12-iPF_{2α}-VI) and activities and levels of a broad spectrum of antioxidant enzymes and micronutrients in stroke patients randomized to receive, from stroke onset and up to three months, either vitamin C (200 mg/day) plus aspirin (300 mg/day) or only aspirin (300 mg/day). By the end of the first week, patients treated with vitamin C plus aspirin had higher vitamin C levels (p = 0.02) and lower 8,12-iPF_{2α}-VI levels (p = 0.01) than patients treated with aspirin alone. The significance was maintained for the increase of vitamin C after three months of therapy (p < 0.01). The clinical functional outcome for both groups of patients similarly ameliorated after three months of treatment. We conclude that vitamin C, at the dose of 200~mg/day and in conjunction with aspirin, significantly decreases ischemic stroke-related lipid peroxidation in humans. Further studies are warranted to clarify whether the use of vitamin C may add clinical long-term beneficial effects in patients with stroke. [ABSTRACT FROM AUTHOR]