The authors compared the frequency of structural and functional heart abnormalities assessed using transthoracic echocardiography among persons with Alzheimer's disease, vascular dementia, stroke, and healthy control subjects. Compared with controls, patients with Alzheimer's disease were more likely to have aortic valve thickening, aortic valve regurgitation, left ventricular wall motion abnormalities, left ventricular hypertrophy, and reduced ejection fraction. Persons with vascular dementia were more likely to have aortic valve regurgitation, but mitral valve thickening and tricuspid valve regurgitation were also more frequent. In the absence of dementia, persons with stroke differed from controls by more frequent mitral valve calcifications. With the increasing prevalence of Alzheimer's disease and vascular dementia, clinicians have to be more attentive to the presence of structural heart disease and its complications in persons with these conditions.