Physostigmine was administered orally 1 mg q.i.d. for one month to 8 patients with a clinical diagnosis of Alzheimer's presenile dementia. The possible beneficial effects of the drug were evaluated by means of a neuropsychological battery administered to all patients before and after treatment. The performances obtained by demented patients on retest did not show any difference in comparison with performances obtained on the first neuropsychologic assessment. Some implications of these negative results are briefly discussed.