Increasing evidence supports the theory that oxidative stress plays an important role in the pathogenesis of Alzheimer's disease (AD). Homocysteine (Hcy), uric acid (UA), bilirubin, and albumin are simple laboratory parameters that are related to oxidative stress. In this study we compared serum Hcy and antioxidant levels in patients with AD and normal cognitive function. In this cross-sectional study, 143 AD patients and 1,553 patients with normal cognitive function aged 65 years and over were enrolled. Mean values of UA and albumin levels of AD patients were significantly lower than normal cognitive function subjects (p: 0.003 versus p < 0.001, respectively). Mean value of Hcy levels of AD patients was significantly higher than normal cognitive function subjects (p = 0.031). Multivariate regression analysis revealed that Mini-nutritional assessment short form (OR: 0.905, 95% CI: 0.850-0.965, p = 0.002), hypertension (OR: 1.573, 95% CI: 1.148-2.155, p = 0.005), UA (OR: 0.879, 95% CI: 0.788-0.981, p = 0.021), Hcy (OR: 1.040, 95% CI: 1.022-1.059, p < 0.001), and albumin (OR: 0.505, 95% CI: 0.339-0.753, p < 0.001) were independent variables predicting the occurrence of AD. Our study supports the hypothesis that a decrease in antioxidants and an increase in oxidative damage are linked to AD.