Background: Oxidative stress after ischemic stroke contributes to neuronal cell injury. We tried to demonstrate an association between total antioxidant capacity (TAC) levels and outcomes after acute ischemic stroke (AIS). Methods: We enrolled 60 patients (36 females and 24 males) who were admitted to our hospital due to AIS, in addition to 30 age and sex-matched healthy controls. TAC levels were measured on day 1 of stroke onset, the relationships between TAC levels, stroke subtypes, and clinical outcomes based on the National Institutes of Health Stroke Scale and modified Rankin scale upon discharge were evaluated. Results: TAC levels were significantly lower in AIS patients than control (P < .001) being much lower in patients with large-vessel cerebral infarction than in those with small-vessel infarction. We investigated whether TAC concentrations reflected the severity and outcome of ischemic stroke and we found a significantly lower concentration of TAC in the poor outcome group than in the good outcome group (P < .001). Conclusions: Our findings suggested that the biochemical changes related to TAC and oxidative stress may be considered a marker of ischemic brain injury and clinical outcome of ischemic stroke.