Physostigmine (0.25 mg-1 mg), arecoline (2 and 4 mg) and saline were administered intravenously over 30 minutes in a randomized double blind design to 11 patients with a clinical diagnosis of Alzheimer presenile dementia. Significant improvement was seen on a picture recognition test with physostigmine 0.375 mg and arecholine 4 mg. A trend towards improvement was also seen with physostigmine 0.25 mg and 0.75 mg, and arecholine 2 mg. For the majority of the patients improvement was only slight but in two patients it was clear cut and consistent.