1. Treatment of patients with dementia of the Alzheimer type (DAT) with arecoline, a muscarinic cholinergic receptor agonist, reportedly improves performance on a picture recognition memory task, but not on other memory measures. To examine further possible performance improvements following arecoline treatment, patients with DAT were treated with a 30 min intravenous infusion of arecoline (5 mg). 2. Psychometric testing was done at five time points (two before and three following the infusion). Patients were tested on a memory task (Buschke selective reminding) and a test of visuo-spatial performance (figure copying). 3. No net change from baseline was seen in mean scores following arecoline infusion. However, the changes in performance on the two tasks were correlated (p less than 0.02) over subjects at 10 min but not at 1.5 or 5.5 hr following the infusion. 4. This result suggests that although individual patients vary in their response to a given dose of arecoline, their responses are consistent across types of tasks. Thus the lack of a mean drug effect may be due to individual differences in response rather than to a lack of response.