In a case/control study, serum concentrations of vitamins A and E and major carotenoids were determined in patients with Alzheimer's disease, multi-infarct dementia and control subjects. The results showed that both Alzheimer's and multi-infarct dementia patients had significantly lower levels of vitamin E and β-carotene than controls (vitamin E: 18.65±3.62 μmol/l in Alzheimer's disease and 15.80±6.93 μmol/l in multi-infarct dementia versus 30.03±12.03 μmol/l in controls; β-carotene <0.13 to 0.42 μmol/l in Alzheimer's disease and <0.13 to 0.30 μmol/l in multi-infarct dementia versus 0.13 to 1.53 μmol/l in controls). Vitamin A was significantly reduced only in the Alzheimer's patients (1.56±0.78 μmol/l in Alzheimer's disease versus 2.13±0.86 μmol/l in controls).