It has been suggested that oxidative injuries have important role in the pathogenesis of Alzheimer's disease (AD). In this study, we assess whether the plasma levels of albumin, bilirubin, and uric acid would be altered in the AD patients compared to those of the healthy controls. Furthermore, we tried to find the correlations between plasma antioxidant levels and the cognitive function in AD patients. The plasma albumin, bilirubin, and uric acid levels were measured by standard methods in 101 AD patients and 101 healthy controls. The Korean version of Mini Mental Status Examination (MMSE–K) was used to evaluate the cognitive functions of AD patients. A significant reduction in the albumin, bilirubin, and uric acid levels in the AD group was found compared to those of the control group. The scores of MMSE–K showed the positive correlation with albumin level in the AD group after adjusting confounding factors such as body mass index, gender and age. This study showed that oxidative injuries would be involved in the pathogenesis of AD, as well as indicating that some antioxidant might be associated with the cognitive functions in AD.