This study was carried out to assess the nutritional and plasma antioxidant status of Alzheimer's inpatients compared to age-matched controls by means of anthropometric measurements, neuropsychological and nutritional tests and plasma biomarkers. Assessment of nutritional biomarkers of prooxidant/antioxidant balance in patients with AD as well as nutritional status and neuropsychological evaluation are important since many studies have demonstrated their association with cognitive impairment. This cross sectional study was carried out in 35 subjects recruited in a geriatric institution in Pavia, Northern Italy. Cases mean Body Mass Index (BMI) was lower than controls' one as well as mid arm circumference, triceps skinfold and arm muscle circumference. Both inpatients MNA and MMSE mean scores were lower than controls ones. Plasma levels of lutein plus zeaxanthin, beta-cryptoxanthin, lycopene, alfa tocopherol, ascorbic acid were significantly lower (p < 0.05) in AD in patients as well as superoxide desmutase and glutathione peroxidase concentrations, while all the other biochemical markers levels did not differ. Plasma antioxidant levels and activities were decreased in AD and could be biologically predictive of an early mild cognitive decline, suggesting early intervention on dietary antioxidant intake.