We evaluated the neuropsychological functions, rate of disease progression, and psychiatric characteristics of 22 patients with probable Alzheimer's disease in whom periventricular white-matter radiolucencies (PWMRs) were seen on the computed tomographic scan of the brain and compared them with 22 matched patients with Alzheimer's disease without PWMRs. Executive/attention, lexical/semantic, memory/learning, and visuospatial functions did not differ between the two groups at baseline or at the 1-year follow-up examination. The frequency of major depression, delusions, and hallucinations did not differ between the groups. However, patients with PWMRs had significantly higher Hachinski Rating scores at both visits and were more likely to develop cerebrovascular disease during follow-up than were controls with Alzheimer's disease. These preliminary results suggest that the presence of PWMRs is not associated with specific cognitive and psychiatric features or with an altered rate of progression of Alzheimer's disease but does predict the development of clinically significant cerebrovascular disease.