Donepezil is a cholinesterase inhibitor used for the treatment of patients with mild to moderately severe Alzheimer's disease (AD). The purpose of this study was to determine the effect of treatment with donepezil 5 mg qd on cognitive evoked potentials (EPs) of patients with AD. Although treatment with donepezil did not normalize EP latencies, treatment was associated with a significant decrease in the auditory P300 latency (mean latency pretreatment=401.5 msec; posttreatment=392.7 msec.; P=0.04), and the visual P300 latency (mean latency pretreatment=605.7 msec; posttreatment=580.3 msec; P=0.04). Treatment with donepezil had no discernible effect on auditory or visual P300 EP amplitudes.