OBJECTIVE: To report a case of the successful use of donepezil for treatment of cognitive and noncognitive symptoms in a patient with dementia with Lewy bodies. CASE SUMARY: An 86-year-old white woman with dementia was experiencing early-onset significant fluctuation of her cognitive status, functional impairment, visual hallucinations, aggression, and parkinsonism. She was intially diagnosed with Alzheimer disease and Parkinsons disease and prescribed donepezil 5 mg/d and benztropine 1 mg twice daily. On reexamination of the case by a neurologist, the diagnoses were revised to dementia with Lewy bodies. The benztropine was discontinued, and donepezil was increased to 10 mg/d. The patient's cognitive and functional status significantly improved, as did her visual hallucinations. DISCUSSION: This case supports previous reports of the marked responsiveness of patients with dementia with Lewy bodies to acetylcholinesterase inhibitors. This may be explained by the marked cholinergic deficit observed in patients with dementia with Lewy bodies and the evidence linking cognitive as well as noncognitive symptoms to this deficit. CONCLUSIONS: The present case suggests that patients with dementia with Lewy bodies respond well to acetylcholinesterase inhibitors. Controlled trials are necessary to further define the role of these drugs for this disease.