Oxidative stress-induced damage to neurons may contribute to cognitive deficits during aging and in neurodegenerative disorders. Schizophrenia has a range of cognitive deficits that may evolve from oxidative stress, and this study examines this association of oxidative stress with cognitive deficits in schizophrenia. We recruited 296 chronic schizophrenia patients and 181 healthy control subjects and examined the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and plasma total antioxidant status (TAS) in both groups. Schizophrenia symptoms were assessed using the positive and negative syndrome scale (PANSS). Our results showed that TAS levels were significantly lower in patients than controls (179.6±81.0U/ml vs. 194.8±46.0U/ml, p<0.05). Cognitive scores on the RBANS and nearly all of its five subscales (all p<0.001) except for the Visuospatial/Constructional index (p>0.05) were significantly lower in schizophrenia patients than normal controls. For the patients, TAS was inversely associated with some domains of cognitive deficits in schizophrenia, such as Attention and Immediate Memory. Our findings suggest that oxidative stress may be involved in the pathophysiology of schizophrenia, and its associated cognitive impairment.