We compared CSF and serum levels of iron, copper, manganese, and zinc, measured by atomic absorption spectrophotometry, in 26 patients patients with Alzheimer's disease (AD) without major clinical signs of undernutrition, and 28 matched controls. CSF zinc levels were significantly decreased in AD patients as compared with controls (p < 0.05). The serum levels of zinc, and the CSF and serum levels of iron, copper, and manganese, did not differ significantly between AD-patient and control groups. These values were not correlated with age, age at onset, duration of the disease, and scores of the MiniMental State Examination in the AD group. Weight and body mass index were significantly lower in AD patients than in controls. Because serum zinc levels were normal, the possibility that low CSF zinc levels were due to a deficiency of dietary intake seems unlikely. However, it is possible that they might be related to the interaction of beta-amyloid and/or amyloid precursor protein with zinc, that could result in a depletion of zinc levels.