Down's syndrome involves age-dependent neuropathological and neurochemical changes similar to Alzheimer's disease, with cholinergic deficits being the most consistent. There is currently no proven treatment for Down's syndrome. We investigated the effect of nicotine-agonistic stimulation with 5 mg transdermal patches, compared with placebo, on cognitive performance in five adults with the disorder. Improvements possibly related to attention and information processing were seen for Down's syndrome patients compared with healthy controls. Our preliminary findings are encouraging, although not generalizable because of small numbers.